Hypersonic weapons and the future of nuclear deterrence

It is widely accepted today that hypersonic weapons pose insurmountable challengesto nuclear deterrence. Although speed has always been a critical factor in warfare, thedevelopment of hypersonics provides unprecedented advantages in terms of the speedand agility of missiles. The increase in the speed and agility of hypersonic missilesdrastically reduces the response time of nuclear states, encouraging the pre-emptive useof force. Two arguments inform the latter claim. The first holds that the speed and agilityof hypersonic missiles are likely to render existing and future missile defences obsolete.The second contends that the failure of missile defences coupled with the reductionof the response time of nuclear states encourages the pre-emptive use of force. Wherenuclear states are unable to field survivable second-strike forces, the stability of nucleardeterrence becomes highly problematic. Besides these arguments, the dual-use nature ofhypersonic weapons ostensibly increases the risk of nuclear escalation. Against this bleakassessment, in this article, the author questions the destabilising effects of hypersonicweapons on deterrence stability, arguing that nuclear deterrence is – and is likely toremain – deeply stable. A thoroughgoing consideration of the strategic implicationsof nuclear weapons provides optimism about the stability of nuclear deterrence inthe face of the development of hypersonic weapons. Two arguments are advanced insupport of the continuing stability of nuclear deterrence. First, missile defences have(and are likely to remain) inefficacious, with the development of hypersonic weaponsmerely reinforcing (rather than establishing) this fact. Second, a would-be aggressorcontemplating the pre-emptive use of force would have to believe that it could destroyall of an adversary’s nuclear force before any can be launched.