Boom, Bling, Backbone, or Blip? The Signaling Inherent in Arms Transfers

Why do states send and seek conventional weapons? Though it may seem obvious that the balance of power motivates states to do so—arms can bolster a state's military power and allow it to engage in or defend during conflict—numerous conventional arms transfers do not conform to the balance of power logic. Consider the F-35 fighter jet, a jet with so many problems that in 2019 the U.S. defense secretary called it “fucked up.”¹ The jet has such severe malfunctions that it “may cause death, severe injury, or severe occupational illness,” according to a report on the plane's ongoing problems.² Although the U.S. Air Force has decided to rely on the older F-16 rather than the F-35 through 2048, many foreign buyers (e.g., Australia, Israel, Japan, the Netherlands, Norway, Singapore, South Korea, and the United Kingdom [UK]) have placed orders for the F-35.³ Given the F-35's per-unit price of $110.3 million, it is puzzling that so many states want it, when they could fulfill their military needs with a cheaper, less problem-prone jet.

Or consider U.S. arms transfers to Ukraine. In March 2018, four years after Russia annexed Crimea but before it invaded Ukraine, the United States sold 210 FGM-148 Javelin missiles to Ukraine. With a range of nearly three miles, these man-portable missiles would have been useful against Russian tanks and helicopters in Crimea and the eastern Donbas region.⁴ But the United States stipulated that the Javelin missiles be stored in a warehouse far away from Crimea or the Donbas and not brought to the front lines. Yet Ukrainian and U.S. officials hailed the transfer; one former U.S. National Security Council (NSC) member said that the Javelin transfer “indicated to the Ukrainians that the US has their back and is willing to up the ante.”⁵ How could weapons that would remain in a warehouse send such an important message?

This article seeks to answer these empirical puzzles. It argues that the motivations for and consequences of conventional arms transfers go beyond balance of power considerations because political leaders understand arms transfers as signals of political alignment.

To explain how signaling dynamics operate alongside balance of power considerations, this article proposes a theory of arms transfers as symbolic signals. First, I created a typology of conventional weapons based on the weapons’ prestige and military utility. I then show that different types of conventional weapons transfers send different signals about the political closeness or distance between the sender and the receiver. Transferring a prestigious and useful fighter jet can signal a deeper political relationship, whereas denying the transfer of an armored vehicle may indicate a rift between sender and receiver. Finally, I show that these arms transfer signals matter because they affect the receiving state's foreign policy behavior and decision-making.

In highlighting the symbolic politics of conventional weapons sales, this article does not discard the importance of the balance of power. Instead, it contributes to debates about signaling and deterrence in international relations. First, it shows that signals can be meaningful even when they are not costly. The central problem of signaling is not credibility, but meaning and resonance: How do relevant actors understand signals?⁶ To create comprehensible messages, actors rely on symbols and shared understandings. The exchange of a diamond ring is different from the exchange of an emerald ring, even though both are costly and credible signals of something. So too does the exchange of a submarine mean something different than the exchange of a jeep. The exchange is a signal of the sender's intentions about investment in a future relationship.⁷ Understanding weapons transfers as the exchange of a symbol better explains why states send and seek arms and helps refine our understanding of how actors communicate their intentions and beliefs.

Understanding the signals sent by weapons transfers also contributes to ongoing discussions about deterrence. How can states communicate will or commitment in addition to demonstrating capabilities? States are never uninterested in balance of power considerations, but they use arms transfer signals to bolster general and immediate deterrence. A receiving state can point to weapons transfers as evidence of alignment with the sender, and it can use that alignment to head off general threats. The strength of political relationships—as signaled by arms transfers—is part and parcel of deterrent calculations.

For policymakers, this article highlights the catch-22 of arms transfers. While providing arms can boost a partner's military power, facilitate joint operations, or help an alliance deter attacks, the signals that arms transfers send have wide-ranging effects on allies and adversaries. Allies will size each other up, jockeying to be the closest ally to their arms-providing partner. Adversaries may want to prevent a political coalition between sender and receiver and act aggressively as a response. Deciding not to sell arms is an equally powerful political move. It is a way to clearly and forcefully express displeasure, or even to indicate a rift between previously close partners.⁸ Policymakers face two dilemmas. On the one hand, they send arms to bolster, but not embolden, allies. On the other hand, signaling that there is a rift between allies might provide an opening for an adversary. But pretending that all is well with the ally could entrap or cause other problems for the sender. Finding the Goldilocks transfer—the one that reassures but does not embolden allies and supports deterrence against adversaries—is the primary puzzle for policymakers.

To show how arms transfers are meaningful political signals, and how signaling operates alongside balance of power concerns, this article examines conventional arms transfers to the Middle East before the 1967 Six-Day War. The years preceding the war saw varied arms transfer requests, approvals, and denials, all during increasing tension between Israel and Jordan, as well as Egypt and Syria. While most explanations of the arms trade focus on the link between arms transfers and the relative balance of power, I show that Israel and Jordan sought arms from the United States for political reasons, and that the United States offered or denied arms transfers because of the signal that the United States hoped or feared the transfer would send. I draw on documents from the U.S. National Archives that reveal the ways that signaling concerns both motivated and constrained U.S. arms transfers and Israeli and Jordanian requests for arms. Arms transfer signals established the political and social hierarchy between the United States and states in the Middle East, including how Israel and Jordan understood their positioning relative to each other.

To explain how and why arms transfers send signals, this article proceeds as follows. First, I examine existing work on the arms trade and show how overlooking the symbolic dimension of arms sales has led to contradictory conclusions about the causes and consequences of arms sales. Next, I develop a theory of conventional arms transfers as symbolic goods and explain which types of arms are most and least symbolically powerful. I discuss how the transfer of these different types of weapons sends signals about political alignments and how signals affect deterrence and foreign policy decision-making. I then apply the theory of arms transfers as signals to a case study of the Middle East from 1955 to 1967. I show that signaling concerns motivated transfers and denials, and that the signals changed the receiver's foreign policy. I conclude with implications for scholars and policymakers.

The conventional arms trade is big business: The top one hundred arms-producing companies sold $592 billion in arms in 2021.⁹ Conventional weapons are the most commonly used tools of war, and they cause the vast majority of conflict-related deaths.¹⁰ As a result, most scholars focus on the immediate downstream consequences of the arms trade, treating conventional weapons as input variables to explain outcomes of interest, such as human rights violations, war onset or duration, and deterrence.¹¹ The overriding assumption is that there are obvious balance of power or economic reasons for the arms trade. Yet this literature has reached mixed conclusions about the effects of arms on conflict-related variables.

Research is similarly uncertain about the relationship between economic variables and the arms trade.¹² One problem is that states have options for obtaining weapons that do not involve exchanging money. The major arms producers, the United States and Russia, regularly provide arms through grant or credit programs. In wartime countries are willing to forgo profit to rush arms to friends.

More recent scholarship has tried to address these questions by focusing on seller or receiver motivations for rather than outcomes of arms sales. Sellers often provide arms to address alliance management dilemmas and to cultivate leverage.¹³ Yet there is evidence that arms transfers do not grant the seller leverage. They instead open avenues for the receiver to extract additional arms.¹⁴ Arms imports, some argue, are determined by the receiver's material dependence on the United States.¹⁵ But the pattern of arms transfers is vague in international relations theories, at times seemingly explained by theories as diverse as self-interest, domestic politics, alliance behavior, political socialization, and conflict initiation. As Richard Johnson and Spencer Willardson point out, explaining the arms trade is “complicated.”¹⁶

Explaining the arms trade is difficult because states seek arms for many reasons beyond the balance of power. For example, the anticipated effects of arms transfers often motivate arms-seeking behavior. This difficulty introduces problems of causality and sequencing. For example, a state fearful of war in the near future will seek arms to help it fight that war. Does this mean that arms transfers are the cause of war? Or is the fear of war the cause of arms transfers? How directly connected to war does the act of seeking or sending arms have to be to identify a causal relationship? Jennifer Erickson notably addresses this issue by explaining that “conventional arms transfers can signal friendship and effectuate alliance between states by demonstrating trust, establishing a security relationship, and enhancing interoperability for joint military operations.”¹⁷ In other words, arms transfers can have multiple possible outcomes besides altering the balance of power, such as cultivating leverage, establishing trust, or signaling friendship. These other outcomes may be just as desirable as the balance of power outcomes of arms transfers themselves (e.g., bolstered deterrence, stronger joint operations, economic security).

There are at least three additional conceptual problems with scholars’ existing treatment of the conventional arms trade. First, existing literature treats “conventional weapons” as a monolithic category, which elides differences across and between weapon types. Conventional weapons are not substitutable for one another: a fighter jet enables a different type of fighting—or deterrence posturing or joint operations—than a submarine or an armored vehicle. Without disaggregating the large category of conventional weapons, it is impossible to explain, for example, why Ukraine wanted U.S.-made heavy battle tanks even though German and British tanks would have been better war-fighting tools for its war against Russia.¹⁸ Nor can existing literature explain why many landlocked states have Departments of the Navy, or why states often buy just a handful of fighter jets.¹⁹ Why states offer or pursue this weapon instead of that one can only be answered by conceptually unpacking the conventional weapons category.

Second, why do states react strongly to the announcement of arms transfers, especially when those arms will not reach the battlefield for months? For example, in December 2022 the United States announced that it would send Patriot missiles to Ukraine. Even though it would be months before Ukraine deployed the weapons, Russia and other observers reacted to this “very significant political statement,” calling it “another provocative move” and warning that it could “entail possible consequences.”²⁰ Existing literature struggles to explain this political reaction to potential changes in an actor's military capabilities. It tends to assume that states can get what they want when they want it, even though it takes months or even years after the sender agrees to a transfer for weapons (and military personnel) to be battlefield ready in the receiving state. According to data collected by the Stockholm International Peace Research Institute, across all weapons transferred from 1950 to 2023, the gap between when artillery was ordered and when it was delivered was 2.7 years, up to a maximum of 33 years.²¹ For aircraft alone, the average gap was 2.8 years, up to a maximum of 43 years.

Finally, existing literature frequently overlooks transfer denials, which often involve decisions that explicitly forgo profit. For example, in March 2022, Poland wanted to give Ukraine its old, Soviet-era MiG planes and purchase newer planes from the United States.²² An aircraft purchase from Poland could have helped the United States recover some of the cost of aid to Ukraine, and the MiGs would not have significantly escalated the conflict in Ukraine or notably changed the balance of power between Ukraine and Russia. The United States killed the deal, however, giving up the potential for profit. Denying transfer requests is only one way that sellers choose to forgo profit. Many sellers prohibit transferring certain weapons that would otherwise find a willing and strong market. The United States will not export the F-22 Raptor fighter jet, despite allies’ interest in purchasing the plane. And in 2019, the nine-state consortium that produces the F-35 decided to cut Turkey from the program after Turkey bought arms from Russia.²³ A conservative estimate is that this political decision cost the United States $500–$600 million and led to production delays across the consortium.²⁴ The reasons to deny arms transfers vary—from protecting critical technologies to punishing misbehavior—and point to the wider political dynamics involved in the arms trade.

To fully explain arms transfers’ puzzles, multiple motivations, and diverse outcomes, scholars need a different approach. First, it is important to break down the category of conventional weapons systematically so that scholars can differentiate between types of weapons (planes versus armored vehicles) and within types (F-16 versus F-35). Second, scholars must recognize that an anticipated outcome is often a motivation for sending/seeking arms (or denying them). Understanding the multiple stages in the transfer process, including negotiation, order/announcement, and delivery, is another piece of the arms transfer puzzle.

Scholars need a theory that explains the process of (non)transfer and focuses on sender and receiver motivations rather than solely on when weapons arrive in the receiving state. I argue that conventional arms have symbolic power that makes their transfer a meaningful signal of political alignment. States send and seek conventional arms for both signaling and balance of power reasons, but researchers have mostly overlooked signaling motivations and effects. This article helps address the issues described above and demonstrates that the political signaling of arms transfers is frequently of equal importance to balance of power considerations.

This section develops a theory of conventional arms transfers as signals. It first disaggregates the broad category of conventional weapons to develop a typology based on prestige and military utility. It then explains the three types of signals that arms transfers can send: maintenance, downgrade, and upgrade signals. Finally, it explains how arms transfer signals affect state behavior and the conditions under which states seek arms for signaling rather than to influence the balance of power.

To explain arms transfers, scholars first need to understand the wide variety of weapons included in the category. Arms as diverse as supersonic aircraft, armored vehicles, cargo planes, and artillery are all conventional weapons. Some weapons are more noticeable than others: Supersonic aircraft, submarines, and main battle tanks get a great deal of attention because they are expensive and “visible.”²⁵ But why these weapons and not others? Scholars and policymakers have an intuitive sense that some weapons are more important or meaningful symbols than others.²⁶ Symbols are the physical representation of an image or idea that is socially constructed: Not all weapons with a certain level of technology or firepower will be symbols.²⁷ Conventional weapons derive their symbolic power from the intersection of prestige and military utility. Disaggregating conventional weapons into these categories of prestige and military utility is a useful way to better understand the reasons why states send and seek particular types.

Prestige is the first conceptual category I develop for understanding the symbolic power of conventional weapons. Prestige is a relational and perceptual concept, not linked to economic value or cost.²⁸ There are two main pathways that affect weapon prestige: association with desirable roles, and scarcity.

Leaders view as prestigious those arms that they associate with the status and success of great powers.²⁹ This explains why leaders perceive main battle tanks, fighter aircraft, and submarines as different from other types of conventional categories. Even main battle tanks, which today are less technologically advanced than fighter aircraft or submarines, are prestigious because of their association with the great power wars of the twentieth century.³⁰ Although having tanks does not make one a great power, not having tanks surely takes one out of the running.

Association with great powers is necessary, but not sufficient, for arms to be prestigious. Anthropologists distinguish between “practical” and “prestige” goods; the former satisfy basic survival needs, and the latter are meant for more.³¹ Prestige weapons do more than meet a state's logistics and defense needs. As their association with great powers suggest, prestige weapons are the tools that allow states to act like great powers, often through power projection. Consider refueling planes: They, like fighter jets, are highly technologically sophisticated and require an extraordinary level of skill to pilot. But refueling planes are not prestigious. Instead, they are an example of a practical weapon that fulfills a need like logistics or moving matériel.

The second prestige pathway is scarcity. While associations with great powers or other desirable roles determine if a category of weapons (e.g., fighter planes or tanks) is prestigious, scarcity determines which specific weapons are more prestigious than others within the same category (e.g., F-104 fighter jet versus F-5 jet, or M1A1 tank versus T-92 tank). Scarcity is an important pathway because prestige is relational and there is a finite amount of it in any given context.³² If too many states have access to a prestigious weapon, it loses its prestige and becomes more ordinary. The F-16 fighter jet is a prestigious type of weapon, but it is of lower prestige than the F-22 fighter jet, which the United States does not export. The types of weapons that states view as prestigious can change over time based on weapon availability.

The F-104 Starfighter, a Cold War–era fighter jet, exemplifies weapons prestige. The F-104 was Mach-2 capable, set the world record for speed and altitude of a piloted aircraft, and was nicknamed “the missile with a man on it.”³³ After trying to incorporate the F-104 into Germany's air force, German pilots devised more appropriate nicknames: “the Flying Coffin” and “the Widow Maker.”³⁴ Despite the plane's significant flight problems, U.S. allies such as India, Israel, Jordan, Pakistan, Taiwan, as well as the North Atlantic Treaty Organization (NATO) allies, all sought the plane at various points in the Cold War. The F-104 was, in the words of one U.S. diplomat, a “shiny object” that was full of prestige, even as it repeatedly failed as a military instrument.³⁵

The second conceptual category for understanding the symbolic power of conventional weapons is military utility. Factors such as versatility, efficacy, reliability, portability, and maintenance requirements all affect the military utility of a given weapon. The Chinese-made DF-3 missile is an example of low military utility: It is a medium-range intercontinental missile that has such poor targeting that it cannot hit the broad side of a barn.³⁶ In addition to weapons’ innate characteristics, their military utility also depends on actor-specific factors, such as the receiver's military capabilities, geography, and infrastructure. Singapore's 2007 purchase of 200 Leopard tanks from Germany is an extreme example of military utility. Singapore built an underground storage facility for these Cold War–era tanks; it is unclear how or where Singapore, an island city-state, would use the tanks.³⁷ In other cases, weak bridges, mountainous terrain, or insufficient runways could make certain weapons less useful.

Comparing prestige and military utility yields four categories of weapons, as depicted in table 1. Symbolic power comes from the intersection of prestige and military utility. Boom weapons have the greatest amount of symbolic power and blip weapons the lowest amount.

Boom weapons are highly prestigious and capable and are the most symbolically powerful type of weapon. These weapons include some fighter jets, submarines, main battle tanks, and missile defense systems. Bling weapons are significantly less effective than others of the same type, but they are still considered prestigious. Boom and bling weapons are typically from the same class of weapons, but bling weapons are comparatively less useful. For example, the F-104 jet was ineffective as a defensive interceptor or midair fighter, thus making it a bling weapon. A boom weapon can become a bling weapon if the recipient does not find it useful. For example, main battle tanks are prestigious but not useful in mountainous regions or in places where bridges or roads are too weak to support their weight. Bling weapons still pack a symbolic punch, but they are not quite as powerful as boom weapons.

Backbone weapons are the unsung heroes of military operations but are symbolically weak. For example, the KC-46 Pegasus tanker plane is technologically advanced and important for air operations, but it is not part of a prestigious category of weapons. As a result, it has lower symbolic power than either boom or bling weapons. Finally, blip weapons are low in prestige and military utility, and they have little, if any, symbolic power. This category includes small arms (e.g., submachine and light machine guns, ammunition, and small bombs). Though these weapons do have military utility, they need to be deployed in large quantities, and usually in conjunction with other weapons, to be as useful as weapons in the other categories.

Understanding the different symbolic values of arms is essential to explain why states send and seek conventional weapons. Transferring symbolic goods allows states to engage in symbolic politics, or “the maintenance or transformation of a power relationship through the communication of normative and affective representations.”³⁸ States ask: What will sending (or accepting) this weapon mean about my relationship with my partner?³⁹ The motivation is the signal that is sent when actors exchange symbolic goods and engage in symbolic politics. Note that the signal does not always have to represent a gain—states can send signals that represent a downgrade or end to a relationship.

With the four categories of weapons in mind, this section explains how different types of weapons transfers send different signals. To do this, it is important to first understand the baseline relationship between the sender and receiver: International politics do not happen in a vacuum, and an arms transfer is rarely, if ever, the de novo political event between two states. As with any item that has symbolic power—whether a diamond ring or a fighter jet—the existing relationship between sender and receiver provides context for understanding the message contained in the exchange of that symbolic good. Just as one would not expect to receive a diamond (or emerald) ring from an acquaintance, states base their expectations on existing relationships.⁴⁰ The less politically aligned they are, the more surprising it would be to receive a symbolically powerful boom or bling weapon.

In general, I expect close friends and allies to trade all types of weapons, especially boom weapons. Denying transfers is unexpected; as Lawrence Freedman observes, doing so is “a calculated insult” and major political act.⁴¹ Among close friends and allies, a denial can be more meaningful and significant than a transfer approval.

By contrast, states that are neither allies nor enemies expect to trade arms of lower symbolic power, such as backbone and blip weapons. While the lesser symbolic power of backbone and blip weapons does not signal a deep connection or robust relationship, bling weapons are useful for within-group differentiation. States can use bling transfers to draw hierarchical distinctions between states, marking one (group) of states as more important than another (group).⁴² Transfers are rare, or nonexistent, between adversaries.

The type of signal sent by a transfer depends on whether the weapon is unexpected or expected. For example, transfers that are in line with existing relationships are expected and send a maintenance signal. These transfers indicate that nothing has changed; the relationship continues.

Unexpected transfers change the recipient's assessment of its relationship with the sender. A transfer that is unexpectedly positive—such as receiving a boom weapon when the existing relationship suggests backbone—sends an upgrade signal. These signals change how the recipient assesses its political relationship because they indicate a growing closeness and potential for further collaboration and support. States that receive upgrade signals should explore avenues of cooperation and mutual support. Transfers that are unexpectedly negative—such as a transfer denial or receiving a lower category of weapon than seemed warranted—send a downgrade signal. This signal indicates a weakening political relationship between the sender and receiver, which forces the receiver to change its assessment of its relationship with the sender. The unexpectedness of the downgrade signal indicates that not all is well between the sender and the receiver. The receiver should pause, reassess, and explore ways to repair the rift with the sender.

Beyond the sender-receiver dyad, upgrade and downgrade signals are of interest to observing states (allies or adversaries) who want to know more about the extent and depth of the political relationship between the sender and the receiver.⁴³ Observing states are particularly interested in the divergence between what the sender or receiver says and what the arms transfers communicate. They will view a receiver that brags about a tight relationship with the sender but then receives a downgrade signal as less credible and more vulnerable than one that accurately identifies its relationship with the sender.

This section developed a way to categorize conventional weapons and to show that symbolic power comes from the intersection of prestige and military utility. It then used the existing political relationship between states to identify three different types of signals that arms transfers can send (maintenance, upgrade, and downgrade). But this theorization raises the question of effect and relevance. Do the signals sent by arms transfers affect state behavior or decision-making? When are states interested in arms transfers for signaling rather than for balance of power or military force posture reasons?

Upgrade, downgrade, and maintenance signals clarify the depth of the relationship between the sending and the receiving states. As a result, the signal affects the behavior and decision-making of both the receiver and observing states, even as the specific manifestation of that change depends on the receiving state's foreign policy apparatus and internal processes.

upgrade signals. Upgrade signals are rare and valuable; they indicate a growing closeness and alignment between the sender and the receiver. The receiver should explore additional ways to politically, economically, or militarily tighten and confirm the upgraded relationship—for example, providing more vocal support for the sender's or the receiver's policies or desires, particularly in international organizations; establishing trade agreements or knowledge-sharing; or conducting joint exercises and training and expanding access to military bases.

Upgrade signals also affect the foreign policy of the receiving state by making it more risk acceptant. As opposed to the predictions of prospect theory, this behavior is not in the rational domain of gains and losses.⁴⁴ It is more emotional, determined by the feelings of security and confidence that come from an upgrade signal.⁴⁵ More confident in their relationship with the sender, receivers are willing to run the risk of higher costs and to use coercive means against adversaries. States with revisionist aims might more aggressively pursue those aims and be more willing to challenge other states. Behaviors directed toward adversaries could include issuing more or more demanding compellent threats, using a larger number of military forces, being more rhetorically belligerent, or showing a greater willingness to escalate disputes, especially when they know the sender will support these actions.⁴⁶ A revisionist state might try to provoke an adversary into attack, thus allowing the receiver to invoke mutual defense agreements that would yoke the sender into fighting alongside it.⁴⁷ After receiving an upgrade signal, states with more status quo orientations should be steadfast when challenged by adversaries, issue more deterrent threats, quickly mobilize forces in response to aggression, and be more rhetorically belligerent during disputes.⁴⁸ These states want to demonstrate their satisfaction with and ability to defend the status quo.

Because upgrade signals increase the risk tolerance of the receiving state, they are risky signals to send. The sender might not know just how aggressive the receiver will become, or how this aggression will manifest. Upgrade signals should empirically be the least common type of signal: Senders do not want to endorse aggression or risk being dragged into conflict.

downgrade signals. Downgrade signals, on the other hand, indicate that the sender perceives a growing rift with the receiver. Receiving states should act to repair this rift, including using intelligence gathering and diplomacy to understand the source of the rift. Other actions could include trying to firm up existing treaties or agreements, shifting policy to bring the sender and the receiver closer together, or, if repairing the rift fails, states might seek an alternate partner.

Downgrade signals affect the foreign policy of the receiving state by decreasing its risk tolerance. Fear of the future will motivate both revisionist and status quo states, especially if they are unable to repair their rift with the sender. In the short term, revisionist states that receive a downgrade signal should chart a path of independence from the sender. Receivers will seek to achieve their goals now, before they lose their ability to make changes to the existing state of affairs. Status quo receivers seek to preserve as much of the status quo as possible, knowing that they can no longer count on the support of the sender. They will often seek a compromise with adversaries. Status quo states are likely to be less offensively postured, less rhetorically belligerent, and more willing to initiate or agree to negotiations.⁴⁹ These states will try to consolidate their positions by reinforcing borders, quickly signing trade or diplomatic agreements, and other moves that will help them retain their core interests before they become more vulnerable to an adversary's coercion.

Downgrade signals often leave a deeper and longer-lasting impression on the receiver and observing states than do upgrade signals. As with a negative Yelp or teaching review, negativity bias often causes downgrade signals to leave a deeper and longer-lasting impression on a leader's perception of its relationship with the sender. Negativity bias also means that leaders tend to “learn” more from negative information than from positive information.⁵⁰ Leaders take negative information as more “true” than positive information, even if that information comes from the same source.⁵¹ The result is that downgrade signals can more significantly damage a political relationship than upgrade signals can repair it. Importantly, the receiver will view a downgrade signal as more damaging than the sender may have intended, since the receipt of negative information carries more weight than the act of giving negative information.

maintenance signals. Maintenance signals indicate that nothing has changed in the relationship between the sender and the receiver. There should be no foreign policy change. Yet the type of weapon that sends a maintenance signal may change over time. As with social relationships, a gift that indicated closeness at the beginning of a relationship will not indicate that same closeness as time goes on. States, like people, expect to receive more meaningful items as the relationship continues. A receiver that was content with backbone weapons will, over time, expect bling and eventually even boom weapons. Both the sender and the receiver need to continually work to maintain the status quo.

When and why are states interested in arms transfers’ signals? After all, arms can increase the relative military power of a state, and as explained earlier, the balance of power is the primary competing explanation for arms transfers.

States are always interested in arms transfer signals and the balance of power, but their relative interest in one compared with the other shifts on the basis of a conflict's likely time horizon. Whether conflict is unlikely, a real possibility, or actually unfolding, the signal and deterrence are connected: Deterrence is as much about communication as it is about capabilities, and arms transfers can influence both pathways. Arms transfers therefore always affect general deterrence because messages about political support and alignment can affect the general, diffuse challenges that the receiver faces. If tensions begin rising and conflict seems likely in the near future, arms transfer signals affect immediate deterrence; receivers are equally interested in both the signal and the capabilities provided by an arms transfer. In these tenser environments, the receiver wants to deter a specific state(s); thus, the receiver is concerned with its relative capabilities against those of its likely adversaries. When war is imminent or during outright conflict, states are primarily interested in their war-fighting capabilities. Immediate deterrence has failed, and only intra-war deterrence is possible; receivers are less interested in signaling than in the balance of capabilities.

Table 2 presents three ideal-types of conflict time horizons: when conflict is in the distant future, when conflict may occur soon, and when conflict is imminent. It shows when states are interested in signals, capabilities, or both.

conflict is distant. When conflict is only a distant possibility, the receiver's primary interest is the arms transfer signal. The sender and receiver communicate their political relationship through arms transfer signals. It is an environment of general deterrence, when adversaries base their balance of power calculations primarily on political relationships and the anticipated support and assistance that the sender would provide the receiver.^{52 As Alexander} George and Richard Smoke explain, deterrence is “primarily a question of influencing the opponent's political calculus … rather than simply threatening overwhelming military costs.”⁵³ States use and display their commitments and political alignments to prevent any conflict or potential challenger from arising. As a result, the receiver is willing to accept arms with limited battlefield use if those arms come with a desired signal. Arms transfer announcements are important to the receiver because they are an early signal of its political ties to the sender. This signal is reinforced and strengthened when the sender delivers the weapon. The operational timeline—the amount of time it would take the receiver to integrate the weapon into battlefield operations—is less important during peacetime. Therefore, the receiver is more willing to accept arms that require more maintenance and time to train personnel. States are always highly sensitive to upgrade signals. Senders often hesitate to send these powerful signals because the signals influence how all states understand the political relationship between the sender and receiver. But a receiver's interest in an upgrade signal will, when conflict is distant, cause a greater willingness to accept bling weapons, so long as they come with the desired signal.

The deal by the United States and the UK to provide nuclear-powered submarines (boom weapons) to Australia (under the 2021 trilateral security partnership, AUKUS) is an example of an upgrade signal in a time of distant conflict. Australia will be only the second ally to receive U.S. nuclear submarine technology.⁵⁴ Unsurprisingly, the sending states emphasized that the deal would boost Australia's military capabilities. But leaders also focused on how the deal signaled the parties’ strengthening ties and commitment to one another. For example, the British prime minister said, “The U.K., Australia, and U.S. are natural allies—while we may be separated geographically, our interests and values are shared. The AUKUS alliance will bring us closer than ever, creating a new defense partnership.”55 In the words of President Joe Biden, “Our unprecedented trilateral cooperation, I believe, is testament to the strength of the longstanding ties that unite us.”56 As both analysts and the media noted, the AUKUS deal is a tangible demonstration of alliance commitment.57 Australia has not yet received its nuclear-powered submarines, and it will require years to adequately train its personnel to be able to safely operate them.

conflict is soon. As tensions rise, and conflict seems a near possibility, states transition from general deterrence to immediate deterrence and calculate the balance of power as a combination of military power and political relationships.⁵⁸ States weak in one will seek to bolster the other, and the arms transfer message (especially when it demonstrates the sender's commitment to the receiver) matters just as much as capabilities.⁵⁹ While receivers are still willing to accept less useful bling arms that come with a desired signal, they would prefer arms that are useful and send a signal (e.g., boom weapons). The operational timeline is more important because fears of war loom larger. If the adversary believes that the receiver will be better armed in the future, they may act now rather than wait. As a result, the announcement of a transfer can still be an important signal, but states are more sensitive to the length of time between when the sender announces the deal and delivers the arms. Longer delivery windows can make the receiver nervous; it may even interpret the delay as a downgrade signal. The receiver will still seek transfers that send an upgrade signal because they demonstrate support from the sender, which bolsters the receiver's immediate deterrence.

U.S. arms transfers to Taiwan fit in this category. War is possible, and while both China and Taiwan care about the military balance in the Taiwan Strait, Taiwan often seeks arms that are more symbolic than militarily useful. Taiwan's best chance of defending itself against China is to pursue a “porcupine strategy,” deploying surface-to-air missiles, air defense systems, and surface-to-sea missiles.⁶⁰ Yet Taiwan has pursued boom fighter jets from the United States. Though Taiwan could use these fighter jets to prevent China from obtaining air superiority, Taiwan and China focus on the political meaning of potential fighter jet transfers. In 2019, for example, when the Donald Trump administration announced the sale of F-16 jets (boom weapons) to Taiwan, U.S. officials emphasized the signaling dimensions of the deal. A bipartisan statement from the U.S. House Foreign Affairs Committee explained, “The sale of F-16s to Taiwan sends a strong message about the US commitment to security and democracy in the Indo-Pacific.”⁶¹ The U.S. Senate noted the importance of the planes’ capabilities and the signal, explaining that the jets would help deter China and improve Taiwan's control of its airspace, while also showing that “the United States remains firmly committed to supporting [Taiwan's] defense.”⁶² In Japan, news articles reacted more to the arms transfer signal than to the transfer's effect on the military balance, even though the United States would not deliver the jets until 2021 at the earliest.⁶³ One analyst said that the F-16 deal was “symbolic” and a “political shock” rather than a military shock to China.⁶⁴

conflict is imminent. When conflict is imminent or has erupted, immediate deterrence has failed and the state's primary interest shifts to winning the war. Capabilities are the priority, though there can be moments when signaling matters. Receiving states want boom and backbone weapons that are militarily useful and can quickly aid their war effort, which means that they want short operational timelines and a condensed timeframe from announcement to delivery. In general, the transfer announcement is more likely to affect the actions of the adversary than those of the receiver: The adversary may anticipate upcoming changes to the receiver's capabilities and adjust its strategy accordingly. Yet transfer announcements are useful to the receiver because they signal its partner's political commitment and interest. If the sender pauses the transfer or changes the quantity or quality of arms, it can signal that it is exhausted or disinterested in helping the receiver's war efforts. This will affect the receiver's war strategy and military power. Longer conflicts have greater opportunity for intra-war deterrence, allowing the receiver to draw red lines within the war itself: A transfer that significantly boosts the receiver's military power can send an upgrade signal about the sender's ongoing commitment and force the adversary to back down.⁶⁵ Recipients seek maintenance signals to show the adversary that their and their partner's commitment is still strong, and they seek upgrade signals to ensure that they will have solid political partners after the war. They therefore focus on the immediate challenge of war, but with an eye toward communicating the broader strength of their political relationships.

Arms transfers to Ukraine are a good example of signaling during conflict. Ukraine repeatedly pushed for arms that would signal U.S. commitment and involvement with Ukraine, even when the money spent to send and acquire those weapons might have been more useful elsewhere. Ukraine was also using arms transfers—and arms denials—as a way to read the tea leaves about its potential membership in NATO. First, shortly after the war began, Poland offered to give Ukraine all of its own MiG-29 fighter jets. The United States quashed this deal because it was concerned that Russia would view it as escalating U.S./NATO involvement in the war. According to a Pentagon spokesperson, “The transfer of combat aircraft could be mistaken for an escalatory step.”⁶⁶ Even while the United States and Poland focused on the capabilities of the MiGs, they were concerned about the signal sent by a boom weapon transfer. Ukraine's interest in old Polish MiGs puzzled the Biden administration. The United States believed that Ukraine would benefit from other types of weapons rather than jets that would not actually help Ukraine's war effort.⁶⁷ One analyst noted that the smaller, ground-based backbone and blip weapons that Ukraine truly needed were “less exciting for photo ops and such.”⁶⁸ European Union officials believed that the MiG transfer might have been possible, if it had been kept secret. When Poland first made its offer, Ukraine produced an infographic showing that it would receive more than seventy fighter jets from Poland, Bulgaria, and Slovakia—even though the only offer on the table was for a handful of Polish jets.⁶⁹ Taken together, this suggests that Ukraine was interested in both capabilities and signaling something about its commitment from Western powers.

Similar dynamics occurred during Ukraine's search for main battle tanks. The allies could not, for many months, decide whether to provide Ukraine with these boom weapons. Some were concerned that the tanks would escalate the conflict because they would boost Ukraine's capabilities. Ukraine was also interested in using tank transfers to signal to Russia that the Western states did not have war fatigue.

Within NATO, the tank transfer became a signal of intra-alliance cohesion when multiple allies agreed to transfer boom tanks in quick succession. In January 2023, the UK agreed to provide Challenger 2 tanks, which Ukrainian President Volodymyr Zelensky said would “send the right signal to other partners.”⁷⁰ Even though the UK gave Ukraine only 14 tanks, far fewer than the 300 that it desired, this arms transfer signal was important to Ukraine.⁷¹ It continued to push for U.S.-made M1A1 Abrams tanks, even though the consensus was that the heavier Abrams would be impractical for Ukraine because they consumed so much fuel.⁷² Yet in late January, the United States and Germany announced that they would send Abrams and Leopard 2 tanks, respectively. President Biden emphasized the political meaning of the joint announcement, saying that it showed NATO strength and solidarity: “The expectation on the part of Russia is we’re going to break up, we’re not going to stay united. But we are fully thoroughly totally united.”⁷³ Similarly, the Polish prime minister, announcing Leopard 2 tank transfers from Poland, Sweden, and Germany, said, “Poland and Europe stand by your side. We will definitely not leave you, we will support Ukraine until complete victory over Russia.”⁷⁴ In other words, although the tanks were an important military asset, the arms transfer signaled the strength of the NATO alliance and the allies’ ongoing commitment to Ukraine.

It is important to note that Ukraine had already received more than 250 T-72 tanks (boom weapons) from Poland, yet it was still interested in U.S.-made tanks. Of all the tanks on offer to Ukraine, the Abrams was least suitable to Ukraine's geography, which is why Ukrainian tank battalion commanders preferred the German-made Leopard 2.⁷⁵ While there is a potential military rationale for transferring these arms—especially the tanks—it is notable that Ukraine emphasized, and the United States was sensitive to, arms transfer signals.

Arms transfers are thus a crucial but often overlooked factor in deterrence postures. States are always interested in arms transfer signals, even if at times they are more interested in the balance of power. Arms transfer signals frequently have a longer time horizon, and they allow states to shore up their future political prospects even while fighting a war.

The years before the 1967 Six-Day War are a useful case to study competing explanations for arms transfers. On the heels of the 1956 Suez Crisis, the Middle East was facing conflict in the near future. All actors believed that conflict would happen soon and that it was only a matter of time. The conventional wisdom on arms transfers predicts that receiving states pursue arms transfers to bolster their relative military capabilities. By contrast, my theory expects that states in this near future conflict environment are interested in the balance of power and signaling. They should seek arms that will, through their upgrade and maintenance signaling function, bolster immediate deterrence and show the strength of the state's political relationships. The U.S. and French arms transfers to Israel and Jordan are therefore a useful illustration of the theory of arms transfer signals. A case study of the “soon” conflict environment is also useful because a conflict can ramp up—war can become imminent or occur—or ramp down. The pivot possibilities make it an interesting and relatively common scenario from which to examine arms transfers as signals.

Conventional explanations of arms transfers—focused on the balance of power or economics—would struggle to explain arms denials between allies, or transfers of bling weapons between politically distant states. By contrast, understanding arms transfers as signals helps explain why, for example, the United States denied the transfer of armored vehicles to Israel in April 1967, and why France imposed a weapons embargo on Israel before the Six-Day War. Arms transfer signals also explain why Jordan repeatedly asked the United States for the F-104 jet, a bling weapon that would have been less useful for the types of conflicts that Jordan fought. I focus here on Israel and Jordan because their behaviors were most surprising among those of the other states in the Middle East: In April 1967, Jordan reversed course and allied with Egypt and the United Arab Command; in May 1967, Israel surprised its allies by attacking the Egyptian air force. Using documents collected from the U.S. National Archives, I trace the cause and effect of each arms transfer and compare the outcome to both my theory of signaling and balance of power and economic explanations.

Table 3 summarizes arms transfers to Israel from the 1950s through 1967. Israel began to request arms from Western suppliers in the early 1950s, when it sought and received boom weapons, such as AMX-13 tanks and Mystère jets from France. These transfers were widely understood as upgrade signals. The Israeli press hailed France as Israel's new champion, and Israeli diplomat Ephraim Evron explained that “the arms trade between Israel and France was a tangible expression of their growing friendship.”⁷⁶

Although France economically benefited from the transfer because it boosted its domestic production, French and Israeli leaders focused on the transfers’ political significance. As my theory expects, France and Israel took additional actions to secure their new relationship. Shimon Peres, then director general of the Defense Ministry of Israel, was given an office in the French Defense Department, and France and Israel often voted in lockstep (alone) at the United Nations and in less public negotiations.⁷⁷ Writing from the U.S. Embassy in Paris in 1964, Foreign Service Officer John Bovey observed, “France's influence with the Government of Israel is that of a major Ally.”⁷⁸ In other words, the arms transfer of boom tanks and then fighter jets was an upgrade signal; both French and Israeli leaders understood that it indicated a strong France-Israel relationship.

Although Israel and France had close ties during the 1950s, this was not the case with Israel and the United States. The United States did not want to become involved in Middle Eastern politics, but Israeli leaders pushed for arms sales. Although the weapons that Israel sought from the United States had some military value, Israel was significantly motivated by signals. In an environment of near future conflict, Israel valued receiving capable boom weapons, but it also sought bling weapons that would bolster its political relationship with the United States and convince observing states that it was aligned and united with the United States. Multiple Israeli officials appealed to the United States for Hawk surface-to-surface missiles. This transfer would have been an unexpected boom weapons transfer, and thus a strong upgrade signal. As historian Warren Bass observes, Israeli Prime Minister “Ben-Gurion wanted both the missile and the marker.”⁷⁹ The United States finally agreed to give Israel the Hawk in 1962, citing plausible military reasons, and tried to downplay the signaling aspect by stating that the transfer was a one-time action to meet an Israeli strategic military need.⁸⁰

But Israel and observing states understood the upgrade signal. Haim Yahil, director general of the Foreign Ministry, described the transfer as a “dramatic turning point in the history of American-Israeli relations.”⁸¹ Peres called the transfer a “crossing of the Rubicon” and “a valid index of a major swing in the American posture toward Israel.”⁸² Further evidence that the signal mattered came from observing states, which also focused on the arms transfer signal and its political consequences rather than the military outcomes. Egyptian President Gamal Abdel Nasser was, according to the U.S. Ambassador in Egypt, “unperturbed by [the] military implications” of the Hawk transfer, but quite upset by its political implications. Nasser felt that the Hawk transfer signaled the United States taking sides in the Middle East conflict.⁸³ In Beirut, pro-Nasser newspaper al-Akhbar published an editorial that stated, “Arabs can expect to be stabbed in the back by the [United States]. Arabs everywhere should beware of Kennedy.”⁸⁴ As the first transfer between Israel and the United States, and a boom weapon at that, the transfer was a strong signal of a growing political relationship between the two countries. This budding political alignment is what leaders reacted to, especially since Israel was the first non-Western state to receive the Hawk from the United States.⁸⁵

Israeli leaders acted to cement and confirm their relationship with the United States in the wake of the upgrade signal. First, Israel submitted a list of additional arms that it wished to receive from the United States. Most notably, in January 1963, Ambassador Avraham Harman asked the United States to provide tanks for free under the military assistance program.⁸⁶ In Harman's view, the Hawk transfer represented Israel's importance to the United States, and his ask was to determine whether, as a now-close ally, Israel would have access to the U.S. military assistance programs available to other close allies. As the NSC observed, Israel wants “U.S. tanks to symbolize a closer U.S.-Israeli military association [emphasis in original].”⁸⁷ The United States was stunned. In its view, the Hawk transfer was merely to adjust the relative balance of power by filling an important gap in Israel's air defense program; it did not indicate a political shift by the United States. The United States tried to ignore the signal that the boom Hawk transfer sent. But Israel, the United States, and observing states all understood that a boom tank transfer would be an upgrade signal, indicating Israel's growing political ties with the United States. The United States rejected the tank request for this reason.

By 1964, however, the United States determined that Israel had a legitimate military need for the tanks. Though the conflict had not yet occurred, it was a possibility, and the United States did not want Israel's adversaries to exploit balance of power asymmetries. Yet the discourse about sending tanks to Israel reveals two important points. First, even when the balance of power is a reason to send arms, states care just as much about the arms transfer signals. Second, the balance of power can push a sender to consider a weapons transfer that it had previously shied away from because of signaling concerns. For example, the United States denied Harman's request for tanks in 1963 because it would “spook the Arabs.”⁸⁸ In May 1964, the NSC recognized that Israel's military needed the tanks, but “political reasons” prevented the United States from providing them.⁸⁹ As Deputy National Security Advisor Robert Komer explained: “We are already tabbed as Israel's greatest friend and protector, and open U.S. sale of tanks would compromise our relations with Arabs.”⁹⁰ The United States faced a dilemma: It wanted to support Israel's legitimate military needs without becoming its political bedfellow. In other words, all states were concerned about balance of power asymmetries, but the United States was equally concerned about the signal that a boom transfer would send.

To solve this political dilemma, the United States created the “German deal,” which would give Israel its needed tanks but allow the United States to avoid sending an upgrade signal. The United States only wanted to send a maintenance signal. It arranged for Israel to receive M-48 Patton tanks from West Germany rather than directly from the United States. Once West Germany sent the tanks to Israel, the United States would backfill the West German arsenal with newer M-48s. In his instructions outlining the German deal, U.S. President Lyndon B. Johnson wrote, “We intend to see that Israel gets the tanks it needs, but without exposing the U.S. to unacceptable political risk [emphasis in original].”⁹¹ The United States lost money—it used aid and grant programs to fund the newer tanks that it gave to West Germany.⁹² Although Israel would benefit militarily from the tanks, the United States was more concerned about the political signals that the transfer would send. As the NSC observed, a direct transfer to Israel from the United States would “project the image of a de facto alliance [emphasis in original]” with the United States.⁹³

Concerned about the political implications of this transfer signal, the United States insisted that Israel keep the transfer secret. U.S. ambassadors in the region were instructed to tell their hosts that the “sale to Israel would be an exception to our arms sales policy made to prevent significant arms imbalance from posing a threat to peace resulting from overconfidence or from desperation.”⁹⁴ Despite U.S. efforts, Israel leaked information about the German deal, and in July 1965, the United States provided the tanks that otherwise would have come from West Germany. This sent a strong upgrade signal and affected Israel's foreign policy, in line with my expectations.

I expect states that receive upgrade signals to be more confident in how they interact with adversaries and to take actions to cement their relationship with the sender. One of the sticking points between the United States and Israel was that Israel conducted cross-border raids in response to violence along its border.⁹⁵ Israel believed that the raids were a deterrent because they demonstrated that challenges to Israel's security would result in a considerably larger “balance of blood.”⁹⁶ From October 1964 (when tanks first arrived in Israel) to October 1966 (when the United States delivered the remaining tanks), however, neither Israeli infantry nor paratroop units conducted any raids.⁹⁷ Consequently, fatality rates dropped compared with preceding or subsequent years.⁹⁸ While this change is partly because of differences in Israeli leadership—Primer Ministers Levi Eshkol and David Ben-Gurion disagreed about reprisals’ efficacy—it also likely stems from the fact that the tank transfers increased Israel's confidence in having support from the United States. It is almost paradoxical that Israel's upgraded political relationship with the United States and resulting boost to its deterrent posture made Israel more militarily restrained against its neighbors.

Israel certainly could have used the tanks in its raiding operations, but it chose not to. As Israeli diplomat Abba Eban said, the tanks were evidence that the United States was determined to fulfill its assurances.⁹⁹ “The provision of tanks,” he said, “was important both substantively and psychologically.”¹⁰⁰ Israel's change in raid policy reflected its growing confidence in the United States and was a relatively low-cost way to adjust its behavior to please its new ally.

There are two important outcomes to highlight. First, the arms transfer signal was sent despite the sender's attempt to manipulate it. The United States downplayed the significance of both the Hawk missile and Patton tank transfers by saying that the transfer was a one-time event or that the weapon did not indicate a broader political alignment. But the signal was meaningful to Israel and observing states despite this deemphasis. Second, the United States and Israel disagreed about the significance of the Patton tank transfer. Because the United States arranged the transfer through a third party, it hoped that the transfer would send a maintenance signal and indicate no change in the relationship between the United States and Israel. Israeli leaders instead saw this as an upgrade signal. These divergent views on the signal show that there can be a mismatch between the message that the sender thinks it is sending and the message that is received. In this case, there was certainly some wishful thinking on the part of U.S. diplomats.

The divergent expectations affected future U.S. arms sales to Israel. Israel expected arms befitting its (perceived) status as a close U.S. ally. The United States, by contrast, wished Israel would stop asking it for boom and bling weapons. This came to a head when Israel pushed for prestigious fighter jets and bomber aircraft (boom weapons) beginning in mid-1965.

First, Israel asked the United States for the F-4 Phantom jet, a jet that was flown by NATO allies. Unwilling to give Israel weapons that were meant for its inner circle of allies, the United States offered instead the F-5, a more widely flown jet that could be transferred from a European state rather than directly from the United States.¹⁰¹ Israel turned down this offer, and again pushed for Phantoms as well as the A-4E Skyhawk bomber. To put a stop to Israel's repeated requests, the United States agreed to sell twenty-four of an unspecified type of combat aircraft, only if Israel could not find suitable planes from Western European suppliers.¹⁰² This is another example of the United States recognizing a military need for arms but restraining itself because of the signaling consequences of such a transfer.

In search of a signal from the United States, Israel insisted it could not find planes that met its needs from Western Europe; the United States agreed to transfer twenty-four A-4E Skyhawks in February 1966. Yet U.S. officials “admonished Israel's leaders not to view the deal as a nascent strategic relationship” and told Israel to look to Europe and “not to bother [the U.S.] on planes for the next several years.”¹⁰³ They also cautioned Israeli leaders to keep the transfer secret and believed that the transfer would be a maintenance signal. But Israeli leaders viewed the transfer as an upgrade signal, which indicates that their previous perception of closeness with the United States was accurate, and that the United States was finally ready to admit it. Eban called the transfer “a development of tremendous political value.”¹⁰⁴ Another Israeli official said that the Skyhawk sale meant that the United States was “ready for a new form of partnership.”¹⁰⁵

Pleased with what it viewed as a friendship status with the United States, Israel again took political actions to align with its partner. For example, Israel did not object to U.S. arms transfers to Jordan. The United States wanted to cultivate Jordan as a friendly nonaligned state; despite prior enmity with Jordan, Israel refrained from publicly criticizing or reacting negatively to initial U.S. arms sales to Jordan.¹⁰⁶

Table 4 summarizes arms requests and arms sales to Jordan. Like Israel, Jordan wanted to maintain a strong military—though Jordan wanted to be capable of military independence from other Arab nations. Existing in the same near conflict environment as Israel, Jordan was interested in both the balance of power and arms transfer signals. In 1965, the United States agreed to give Jordan M-48 Patton tanks, the same kind that it sent to Israel after the German deal fell apart. The United States believed that this would be a maintenance signal to allow Jordan to uphold its independence from Egypt and the Soviet Union. The transfer enabled Jordan to stand firm and defend the status quo.

Even the New York Times knew that this sale was politically significant, writing that “Jordan presents an illustrative example of the political motivations behind American arms contributions.”¹⁰⁷ Egypt also viewed the transfer as an upgrade signal; Egyptian newspaper Al Ahram indirectly accused the United States of trying to divide the Arab world by giving arms to Jordan.¹⁰⁸ This put Jordan in an increasingly difficult position. Although it felt that the transfer simply supported the status quo, its Arab neighbors viewed the transfer as a meaningful signal that Jordan had aligned with the United States. But Jordan perceived itself as always playing second fiddle to Israel: It received less frequent and more limited types of weapons from the United States than did Israel.

Like Israel, Jordan requested additional arms to clarify its standing with the United States. It asked for F-104 fighter jets, bling weapons that were a NATO alliance staple. The United States knew that Jordan had explicit signaling motivations: The State Department explained that Jordan's request was to test how important the United States thought Jordan was to the region.¹⁰⁹ Although the United States denied the F-104 transfer in 1964, by early 1965 it had reconsidered. The United States said it would “sympathetically consider [emphasis in original]” selling the planes to Jordan if Jordan could not find supersonic aircraft from other “Free World sources” to help King Hussein avoid compromising his independence.¹¹⁰ In this statement, the United States recognized both the military and signaling motivations of its arms transfers for Jordan. To maintain its independence, Jordan needed to present a strong outward image, especially in the face of calls for a pan-Arab alliance led by Egypt. Although receiving backbone arms from the United States could help Jordan military, the bling weapons’ arms transfer signal was equally if not more valuable to Jordan because it helped Jordan maintain political independence. By indicating a close relationship with the United States, Jordanian and U.S. leaders hoped Jordan could more easily hold out as a friendly and stable state in the Middle East.

In March 1966, the United States offered Jordan twelve F-104 jets that it would deliver beginning in 1968.¹¹¹ Israel agreed to quietly support the F-104 transfers to Jordan, even though the United States denied its request for the same weapon.¹¹² Israel, too, recognized that both the F-104 transfer signal and having a nonhostile neighbor were highly valuable.

Despite Israel's reassurances that it would support the F-104 transfer, Israeli policy began to shift. Israel believed that the F-104 agreement was an upgrade signal for Jordan, even though the planes would not arrive for two years. Israel also thought that the United States sent it an implicit downgrade signal when it denied Israel's request for the F-104. In response to this confluence of signals, Israel asked for additional missiles for its A-4E Skyhawk planes. The United States offered older Sidewinder missiles rather than the more exclusive Bullpup missiles that Israel requested, although both were boom weapons.¹¹³ The United States based its decision on Israel's military capabilities, explaining that “Israel remains qualitatively superior over any of the various combinations of Arab states with which it could be expected to come into direct conflict.”¹¹⁴ Even though it had agreed to sell arms to Jordan, the United States reassured Israel that it would not become Jordan's primary arms supplier.¹¹⁵ Israel perceived such reassurances as empty and not credible. What mattered more to Israel was that the F-104 bling arms transfer to Jordan was an upgrade signal.

Israel changed its policy on cross-border raids in response to the United States’ upgrade signal to Jordan and perceived downgrade signal to Israel. Israel reacted like a spurned lover, pursuing actions that would force the United States to pay more attention to it. On November 13, 1966, Israel attacked the Jordanian town of Samu. For the first time in years, Israel used paratroopers and infantry as it raided the town, destroying civilian homes and killing fifteen Jordanian soldiers.¹¹⁶ Although the denied arms transfers do not solely explain why Israel changed its policy, it is notable that the raid occurred after two denials. Israeli leaders claimed that the military finally raided Samu after it had not responded to thirteen previous incidents.¹¹⁷ But Eshkol also seemed to indict the United States, expressing frustrations with “friendly” nations “who preach, who offer us advice and express indignation, without making any contribution to the stopping, or even exposure, of Arab aggression.”¹¹⁸

The United States viewed Israel's raid as a betrayal, which affected future arms sales. In March 1967, the United States denied Israeli requests for arms, stating, “It's still too soon after the Samu raid to appear to reward the Israelis.”¹¹⁹ Jordan was equally concerned and made additional arms requests to see how the United States would respond. In a conflict between its friends, would the United States support Israel or Jordan? King Hussein's requests were for an upgrade signal and “tangible show of support” from the United States.¹²⁰ But the United States did not come through. It only provided backbone and blip weapons: six 105 mm howitzers, utility trucks, and fifteen 106 mm recoilless rifles.¹²¹ Coupled with a lukewarm “consolation” letter after the Samu raid, Hussein perceived this as a downgrade signal that indicated the United States would support Israel rather than Jordan.¹²²

King Hussein felt like his world was falling apart: The United States gave him measly backbone and blip weapons, the raid on Samu made him seem weak, and actors within Egypt and Syria were calling for his removal.¹²³ While King Hussein faced a growing crisis owing to the United States’ downgrade signal, Israel requested more arms. In April 1967, it asked for armored personnel carriers, backbone weapons that should have been a straightforward transfer between close friends.¹²⁴ The United States denied the request and refused to decide—essentially, a quiet veto—on Israel's repeated request for the F-4 Phantom jet.¹²⁵

The United States’ downgrade signals directly affected Jordanian and Israeli foreign policy. Hussein made a last-ditch attempt to secure his position. In a major reversal of Jordanian policy, he signed a defense pact with Egypt on May 30, 1967. Even more surprising was that King Hussein approached Nasser to propose the defense pact and agreed to let Egypt command Jordanian troops.¹²⁶ That same day, Israel dispatched the head of its intelligence services on a diplomatic trip to the United States.¹²⁷ He reported back that the United States was not planning any arms transfers, which led Eban to conclude, “We were isolated; none of the powers would come to our assistance.”¹²⁸ France reinforced Israel's feeling of abandonment when it warned Israel not to act and imposed an arms embargo on June 2.¹²⁹ Eban described the lack of support for Israel as “thunderous silence.”¹³⁰ Israel also faced a growing military threat: Egypt mobilized 100,000 troops to the Sinai Peninsula and Gaza, and Syria mobilized 60,000 troops to the Golan Heights.¹³¹ Rather than send arms to a friend in need, President Johnson warned Israel to “abstain from every step that would increase the tension and violence in the area.”¹³² Faced with the twin terrors of abandonment and encirclement, Israel attacked the Egyptian Air Force on June 5, 1967.

There are three important outcomes to highlight in the months before the 1967 war. First, arms transfer signals carried greater weight than words. Even though Israel did not protest U.S. transfers to Jordan, it perceived the United States sending arms to Jordan but not to Israel as a downgrade signal; Israel adjusted its behavior because of that downgrade signal. Similarly, Jordan believed that the United States’ disappointing backbone weapons arms transfer was a downgrade signal that left Jordan scrambling for political support.

Second, the arms transfer signals affected how states in the region behaved, not just the receivers. Jordan reacted to the political meaning of U.S. arms sales to Israel; Israel reacted to the political meaning of U.S. arms sales to Jordan; Egypt and Syria understood the meaning of transfers (and denials) to both. Likewise, both Jordan and Israel were concerned about their political standing relative to each other. Although the balance of power is in part what motivated these states to react to these arms transfers, the leaders attributed their reactions to the perceived signal and its meaning for the political relationship between the sender and the receiver. In fact, some arms requests were specifically to clarify the receiver's position with the United States and to determine who the United States would side with in a dispute.

Third, the United States repeatedly botched its arms transfer signals: It tried to suggest that an upgrade signal was really a maintenance signal; it misunderstood the gravity of Jordan's and Israel's position in May 1967; and it undervalued the meaning that Israel and Jordan attached to arms transfers and denials. Negativity bias may account for this last point—that is, a downgrade signal affects the receiver more than the sender intended.

Arms transfers are as much about the signal sent by the transfer as they are about changes to the relative balance of power. This article has argued that conventional weapons have symbolic power based on their prestige and military utility, and that the transfer of different types of weapons (boom, bling, backbone, or blip) sends signals about the depth of the political relationship between sender and receiver. Arms transfers to Israel and Jordan show that the signal sent and received was just as important as the benefits of acquiring arms: Upgrade signals allowed a confident Israel to pause its policy of reprisals and helped Jordan retain political independence from Egypt and the United Arab Command. Downgrade signals spoke louder than other actions, and Israel's and Jordan's crisis of confidence in their respective relationships with the United States led to political scrambling in April 1967. A disappointed and worried Jordan reversed political course and aligned with Egypt; an abandoned and nervous Israel preemptively attacked the Egyptian air force, kicking off the 1967 Six-Day War. The signals sent by arms transfers—and denials—steered the course of political decision-making that ultimately resulted in conflict. Navigating these signaling dynamics will be an ongoing challenge for states.

These findings have implications for research on arms trade and signaling. First, scholars who study the arms trade need to understand what motivates states to send and seek arms. The balance of power is not the only reason why states engage in arms transfers; each transfer discussed here was sought because of the anticipated outcome. States seek signals of durable and reliable friendship just as much as they seek to boost their military power, which means that sender and receiver motivations are often linked to long-term anticipated effects. Studying the arms trade is not as simple as accounting for what was transferred when: States must simultaneously consider both signaling and military operations. Relatedly, the lengthy time horizon and interplay between the sender's and the receiver's motivations may pose challenges for certain methodological approaches to studying the arms trade. But existing explanations of the arms trade that do not consider these factors are incomplete.

Second, scholars working on signaling need to focus more on the meaning of signals than on a signal's costliness as a proxy for credibility. When the United States sent Hawk missiles to Israel in 1962, it thought the transfer communicated no change to the status quo. Yet Israel believed that the transfers foretold a growing closeness to the United States. There was no debate—within Israel or the United States—about the credibility of the Hawk transfer. The two countries focused entirely on the transfer's meaning—Israel viewed it as a significant upgrade signal, whereas the United States interpreted it as a maintenance signal. Instead of debating what makes a signal credible or not, scholars should focus on how and why actors determine meaning, as well as on the moments when the meaning of the signal is unsettled. Understanding conventional arms transfers as instances of symbolic politics highlights why constructivist and interpretative approaches to signaling and deterrence are important. They clarify how signaling shapes social constructs (e.g., meaning, identity, and relationships). Future research should examine what happens when actors disagree about the meaning of a signal. Such work will help clarify how states think about their deterrence capabilities and intentions.

A corollary implication is that scholars need to factor signal meaning into their balance of power analyses. The power being balanced goes beyond military power: Having certain types of weapons can make a state part of the in-group, which is itself a type of reputational and political capital that affects how both it and other states behave. Arms transfers communicate political alignment in a way that affects a state's general and specific deterrence abilities. Excluding signal meaning from these calculations misses a large part of the story.

Future research on signaling should seek to understand signals’ long-term effects and multi-state implications, including how they affect deterrence postures. Arms transfer signals can have network effects, whereby states reinforce, create, or sever ties with other states.¹³³ This can create status hierarchies, as allies seek weapons to further distinguish themselves from others that are part of the same alliance or partnership network. This intra-alliance jockeying for position leads receivers to expect certain types of weapons; this competition creates additional incentives for receivers to seek arms that have little to do with the military balance or economic cost.

Finally, for policymakers, the findings in this article suggest that arms transfers are indeed a risky business. While sending arms to a friend can help that friend stand strong, it also creates expectations for future transfers. Arms recipients are like the mouse with the cookie: Feed them a little, and they will keep coming back for more.¹³⁴ It is not easy to transfer arms just once. Policymakers should therefore be cautious about approving arms sales. Additionally, once an arms transfer relationship has begun, it takes work to maintain the status quo. Like the mouse, a state's appetite will grow, and it will expect more symbolically powerful arms as time passes. Finally, refusing to send or accept arms is one of the most meaningful signals that a state can send. Policymakers need to fully understand the political consequences of how a receiver might interpret an arms transfer denial.

The author thanks Ronald Krebs for his guidance and feedback on multiple versions of this article. The author also thanks Robert Ralston and the anonymous reviewers for their comments. Previous versions of this article were presented at the 2017 International Studies Association Annual Convention and the 2018 American Political Science Association Annual Meeting.