Nuclear primacy is stabilizing, nuclear parity causes escalation

Moreover, if the United States had fewer nuclear weapons due to a smaller land leg, nuclear deterrence might also be threatened because US adversaries might be more willing to initiate and escalate militarized challenges against the United States and its allies. Nuclear deterrence has long been conceptualized as a game of nuclear brinkmanship. Although nuclear states cannot credibly threaten to launch a suicidal nuclear war, they can credibly threaten to risk one by initiating and escalating crises.12 A state’s willingness to stand firm in these crises depends, in part, on its vulnerability to nuclear war. Recent social-science research shows that states that are more vulnerable to a nuclear exchange are more likely to be targeted with military threats from nuclear-armed states and less likely to achieve their basic goals in a nuclear crisis.13 Accordingly, reducing the size of the US ICBM force would simultaneously increase US vulnerability and decrease adversary vulnerability to nuclear coercion, thereby shifting the balance of resolve toward US adversaries. Adversaries might be more willing to challenge, and stand firm in crises against, the United States, and Washington might be more eager to seek offramps in a crisis.

This resulting shift in the balance of resolve could also increase the risk of nuclear war. The most plausible pathway to nuclear war in the contemporary international security environment stems not from a bolt-from-the-blue strike but from escalation of a conventional conflict. US adversaries might employ nuclear weapons in the event of a conventional conflict in Eastern Europe, in the Indo-Pacific, or on the Korean Peninsula.14 If adversaries are more likely to initiate and escalate crises against a United States with a smaller ICBM force, as argued above, then there is also a greater risk that Washington will find itself in dangerous crises that could spiral out of control and result in a catastrophic nuclear exchange.