The United States has repeatedly debated whether to adopt a nuclear no-first-use (NFU) pledge. Advocates for such a pledge emphasize its potential advantages, including strengthening crisis stability, decreasing hostility, and bolstering nonproliferation and arms control. But these benefits depend heavily on nuclear-armed adversaries finding a U.S. NFU pledge credible. A new theory based on the logic of costly signals and tested on evidence from NFU pledges by the Soviet Union, China, and India suggests that adversaries perceive such pledges as credible only when: (1) the political relationship between a state and its adversary is already relatively benign, or (2) the state's military has no ability to engage in nuclear first use against the adversary. Empirically, these conditions rarely arise. More typically, hostile political relations combined with even latent first-use capabilities lead adversaries to distrust NFU pledges and to assume the continued possibility of being subject to first use. The implication is that changes to U.S. declaratory policy alone are unlikely to convince adversaries to disregard the prospect of U.S. nuclear first use without changes in these countries’ political relationships or U.S. nuclear force posture. The beneficial effects of an NFU pledge are therefore likely to be more minimal than advocates often claim.

Is India shifting to a nuclear counterforce strategy? Continued aggression by Pakistan against India, enabled by Islamabad's nuclear strategy and India's inability to counter it, has prompted the leadership in Delhi to explore more flexible preemptive counterforce options in an attempt to reestablish deterrence. Increasingly, Indian officials are advancing the logic of counterforce targeting, and they have begun to lay out exceptions to India's long-standing no-first-use policy to potentially allow for the preemptive use of nuclear weapons. Simultaneously, India has been acquiring the components that its military would need to launch counterforce strikes. These include a growing number of accurate and responsive nuclear delivery systems, an array of surveillance platforms, and sophisticated missile defenses. Executing a counterforce strike against Pakistan, however, would be exceptionally difficult. Moreover, Pakistan's response to the mere fear that India might be pursuing a counterforce option could generate a dangerous regional arms race and crisis instability. A cycle of escalation would have significant implications not only for South Asia, but also for the broader nuclear landscape if other regional powers were similarly seduced by the temptations of nuclear counterforce.

How do states pursue nuclear weapons? Why do they select particular strategies to develop them, and how do these choices affect the international community's ability to prevent nuclear proliferation? The bulk of the proliferation literature focuses on why states want nuclear weapons. The question of how they pursue them, however, has largely been ignored. This question is important because how states try to acquire nuclear weapons—their strategies of nuclear proliferation—affects their likelihood of success and thus the character of the nuclear landscape. Four strategies of proliferation are available to states: hedging, sprinting, hiding, and sheltered pursuit. Nuclear acquisition theory explains why a proliferator might select one strategy over the others at a given time. Empirical codings from the universe of nuclear pursuers, combined with a detailed plausibility probe of India's long march to acquiring nuclear weapons—including novel details—establish the analytical power of the theory. Different strategies of proliferation offer different opportunities and vulnerabilities for nuclear proliferation and nonproliferation, with significant implications for international security.

A probe of various regional power nuclear postures reveals that such postures, rather than simply the acquisition of nuclear weapons, can have differential effects on deterrence and stability dynamics. The India-Pakistan dyad is a useful candidate for exploring these various effects because the three regional power nuclear postures—catalytic, assured retaliation, and asymmetric escalation—have interacted with each other in South Asia. In particular, Pakistan's shift from a catalytic posture to an asymmetric escalation posture in 1998 against a continuous Indian assured retaliation posture allows the effects of nuclear posture to be isolated in an enduring rivalry in which many variables can be held constant. The asymmetric escalation posture may be “deterrence optimal” for Pakistan, suggesting that nuclear postures do have different effects on conflict dynamics, but it has also enabled Pakistan to more aggressively pursue longstanding revisionist preferences in India, triggering more frequent and intense crises on the subcontinent. Furthermore, the command and control procedures that Pakistan undertakes to make its asymmetric escalation posture credible amplify this instability. These procedures generate risks to the safety and security of Pakistan's nuclear assets, both at present and as India and Pakistan continue to dynamically evolve nuclear and conventional postures. The conclusions for South Asian and international security of this reality are grim.