To the Editors (Tongfi Kim writes):

In “To Arm or to Ally?” Keren Yarhi-Milo, Alexander Lanoszka, and Zack Cooper present an elegant and powerful theory that explains conditions under which a great power (in their case, the United States) offers a client state arms, an alliance commitment, or both.1 Their article does not give due attention, however, to what motivates a patron to provide security assistance to clients in the first place—especially its desire to influence its clients to obtain concessions in military, political, economic, and other policies.2 Below I explain how Yarhi-Milo, Lanoszka, and Cooper's conceptualization of key variables inadvertently plays down the role of influence-seeking in U.S. policy.

First, Yarhi-Milo, Lanoszka, and Cooper's conceptualization of arms transfers does not reflect the wide range of ways in which a patron can support a client and the significant differences among the types of arms transfers with regard to buying influence. Their conceptualization of arms transfers, in which “a state gives another state weapons to augment its military capabilities” (p. 95), “covers multiple methods of provision, including sales, grants, and loans” (p. 97). As they discuss at the beginning of the article, however, the United States spends large sums of money on security assistance worldwide, a significant portion of which is spent on things other than U.S. arms (p. 91). Israel, for example, has been allowed by the U.S. government to use about 26 percent of its U.S. Foreign Military Financing to purchase Israeli weapons.3 Pakistan, in addition to Foreign Military Financing, had received about $13 billion by 2015 in Coalition Support Fund assistance for “operational and logistical support of U.S.-led counterterrorism operations.”4 Because military aid other than arms transfers can increase the military capabilities of clients, it deserves analysis. At the same time, it is problematic not to differentiate sales, grants, and loans in analyzing transactions between allies. For instance, Japan has received more arms from the United States than Israel, but letting Japan buy U.S. arms with Japanese money is much less of a patron's favor to a client than giving Israel money to buy U.S. arms.5

Second, Yarhi-Milo, Lanoszka, and Cooper define “commonality of security interests” as “the extent of the threat that the client's primary adversary poses to the patron's core security interests” (p. 98), but their definition neglects the importance of the patron and client agreeing on how to deal with the adversary. For instance, in the early years of the Cold War, South Korea's and Taiwan's adversaries were also U.S. adversaries, but these clients' preference for offensive strategies posed significant problems for Washington. The United States, therefore, needed to exert influence on both states. In fact, one of the major motivations for the U.S. government in offering an alliance commitment to South Korea was to gain influence over its president, Syngman Rhee, who had tried to sabotage the Korean War armistice.6 Even when a patron shares an adversary with a client, influencing the client remains an important objective.

Third, Yarhi-Milo, Lanoszka, and Cooper argue that the perceived military balance between the client and its main adversary affects the patron's willingness to provide costly arms. They find that policymakers who argued that the military balance did not favor a client or that it was shifting against it advocated costly transfers. It is also plausible, however, that those who would like to support a client use the military balance as a justification. Since the policy transition to costly arms transfers, Israel has received large amounts of military aid from the United States despite Israel's military superiority against its adversaries. It is unclear how much of an advantage would be enough for the United States to reduce this aid. Meanwhile, some shifts in which states receive more U.S. military aid—for example, Pakistan after the terrorist attacks of September 11, 2001—seem to have little to do with the local military balance and are more about buying the clients' concessions to facilitate U.S. policy. In some cases, improving the military balance is less important than buying influence over the clients. Consider, for example, the Camp David accords between Israel and Egypt, and U.S. aid to the two states.

Finally, even though Yarhi-Milo, Lanoszka, and Cooper find in primary and declassified documents that “U.S. decisionmakers often discussed using arms to obtain leverage with Israel,” they dismiss this alternative argument by saying that “U.S. decisionmakers recognized the difficulties associated with using arms for such purposes” (p. 135). Buying influence and deciding how best to use it is difficult, but this does not invalidate the importance of patrons seeking to exert influence over their clients. As Yarhi-Milo, Lanoszka, and Cooper note, future research should further theorize and examine the nature of patron-client relationships (pp. 136–138).7

Tongfi Kim

Brussels, Belgium

Keren Yarhi-Milo, Alexander Lanoszka, and Zack Cooper Reply:

By highlighting some gaps in our argument regarding when great powers offer their clients arms transfers or alliances, Tongfi Kim helpfully outlines how “future research should further theorize and examine the nature of patron-client relationships.”1 We see several opportunities for moving this research agenda forward.

One avenue for future research is disaggregating the meaning of “military aid.” In our article, we sought to examine how patrons choose between two types of commitments often discussed in the existing literature: arms transfers and alliances. We emphasized how alliances can differ in their conditionality and how arms transfers vary in cost, spillover potential, and entrapment risk. As Kim observes, however, “it is problematic not to differentiate sales, grants, and loans in analyzing transactions between allies.” Further research in this area would benefit from heeding his advice on how to address this issue. Scholars should disaggregate military aid to examine systematic variation using theories about the conditions under which sales, grants, or loans are offered.

Scholars could also examine how military aid helps patrons influence their clients. Kim notes that “[e]ven when a patron shares an adversary with a client, influencing the client remains an important objective.” Again, we agree: patrons calibrate their provision of arms and alliances to shape the behavior of potential and actual clients. They take special care in making these decisions, especially when they see the client as posing a serious entrapment risk. Recent work on this phenomenon describes how these dynamics have operated in U.S. alliances with South Korea and Taiwan.2 In our view, influencing clients is important for patrons even when they share an adversary with a client. We wanted to uncover the most effective signaling mechanisms in these cases, so a more fine-grained analysis could be beneficial. Mindful of Kim's first point, future researchers could examine how arms sales, grants, and loans vary in their ability to address entrapment risks.

Investigating the precise role of the military balance in patron-client relationships offers other opportunities for research. Kim asserts that “[i]n some cases, improving the military balance is less important than buying influence over the client.” In citing the cases of Israel, Egypt, and Pakistan, Kim comments that “[b]uying influence and deciding how best to use it is difficult, but this does not invalidate the importance of patrons seeking to exert influence over their clients.” We concur that the United States has often used arms to buy influence over clients—Egypt is a good example. Still, U.S. decisionmakers often invoked the military balance in the documents we consulted for our article. The decision to adopt any policy tool is seldom monocausal, but in our two cases, the provision of arms was not motivated primarily by efforts to exert political influence. Admittedly, we examined only U.S.-produced primary documents. Future research should attempt to reconstruct decisionmaking processes among client states to assess their perceptions of U.S. actions as well as client reactions.

Our article was a first step in pushing back against the tendency to treat decisions to ally or to arm in isolation from each another. Kim elucidates further work that remains to be done on this topic. Such research could not be timelier: scholars and policymakers alike are questioning many of our long-held assumptions about alliances in the wake of the Donald Trump administration's seemingly untraditional approach to managing foreign commitments.

Keren Yarhi-Milo

Princeton, New Jersey

Alexander Lanoszka

London, England

Zack Cooper

Washington, D.C.

Notes

1. 

Keren Yarhi-Milo, Alexander Lanoszka, and Zack Cooper, “To Arm or to Ally? The Patron's Dilemma and the Strategic Logic of Arms Transfers and Alliances,” International Security, Vol. 41, No. 2 (Fall 2016), pp. 90–139, doi:10.1162/ISEC_a_00250. Subsequent references to this article appear parenthetically in the text.

2. 

For a supply-side analysis of security provision through alliances and an argument that emphasizes the importance of nonmilitary concessions in alliance politics, see Tongfi Kim, The Supply Side of Security: A Market Theory of Military Alliances (Redwood City, Calif.: Stanford University Press, 2016).

3. 

Jeremy Sharp, “U.S. Foreign Aid to Israel” (Washington, D.C.: Congressional Research Service, June 10, 2015), p. 6.

4. 

K. Alan Kronstadt, “Pakistan-U.S. Relations: Issues for the 114th Congress” (Washington, D.C.: Congressional Research Service, May 14, 2015), p. 14.

5. 

For “all transfers of major conventional weapons from 1950 to the most recent full calendar year,” see the Stockholm International Peace Research Institute Arms Transfers Database at https://www.sipri.org/databases/armstransfers. As early as mid-1962, the United States tried to offset the adverse balance of U.S. military expenditures in Japan by selling U.S. arms to Japan. See Shingo Nakajima, Sengo Nihon no Boei Seisaku: “Yoshida Rosen” wo Meguru Seiji/Gaiko/Gunji [Japanese defense policy in the postwar era: Politics, diplomacy, military affairs, and the “Yoshida Doctrine”] (Tokyo: Keio Gijuku Daigaku Shuppankai, 2006), p. 240.

6. 

See “President Dwight Eisenhower's Letter to President Syngman Rhee of Korea, Concerning Acceptance of the Panmunjom Armistice,” June 7, 1953, John T. Woolley and Gerhard Peters, eds., American Presidency Project, University of California at Santa Barbara, http://www.presidency.ucsb.edu/ws/?pid=9869.

7. 

It would also be interesting to apply Yarhi-Milo, Lanoszka, and Cooper's argument to the anti-Soviet alliance between the United States and Israel, formed in 1981 and dissolved with the collapse of the Soviet Union.

1. 

Keren Yarhi-Milo, Alexander Lanoszka, and Zack Cooper, “To Arm or to Ally? The Patron's Dilemma and the Strategic Logic of Arms Transfers and Alliances, International Security, Vol. 41, No. 2 (Fall 2016), pp. 90–139, doi:10.1162/ISEC_a_00250.

2. 

Brett V. Benson, Constructing International Security: Alliances, Deterrence, and Moral Hazard (Cambridge: Cambridge University Press, 2012); and Victor D. Cha, Powerplay: The Origins of the American Alliance System in Asia (Princeton, N.J.: Princeton University Press, 2016).