Turn---counterforce strikes are the only scenario for city busting because they provide moral cover to adversaries to retaliate against cities.
Boyd 16, Senior policy analyst, addressing nuclear weapons policy and counterterrorism. His writings have appeared in The Nonproliferation Review, The Washington Quarterly, The Bulletin of the Atomic Scientists, and Studies in Conflict and Terrorism. He earned a master of public policy degree from Harvard’s JFK School of Government (Dallas, Revealed Preference and the Minimum Requirements of Nuclear Deterrence, Strategic Studies Quarterly, US STRATCOM 2016, Available Online at: https://www.airuniversity.af.edu/Portals/10/SSQ/documents/Volume-10_Issue-5/Boyd.pdf)
Whether this concern would apply to countervalue retaliation is unclear. China’s nuclear strategy implicitly involves city destruction, given the limited quantity and accuracy of its long-range weapons. However, qualitative differences between missile attacks and unconventional delivery modes suggest that a discrete use calculation might apply. Not least, an indiscriminate attack against civilians weeks or even months after a provocation would seem particularly cold-blooded. Nonetheless, the credibility threshold for retaliation is presumably far lower than for initiating nuclear war, and one line of thinking in particular may permit recourse to countervalue strikes despite moral qualms about them.
Counterforce capabilities are the luxury of states that spend lavishly on offensive arms, whereas a minimalist posture is the strategy of a more restrained nuclear power. In the event of a nuclear attack, members of the latter group cannot in fairness be expected to refrain from their only available means of retaliating. This would amount to penalizing the victim for adopting a more stable and responsible nuclear posture than its aggressor. Thus, any civilian deaths that result from such a state’s retaliation can be laid squarely at the feet of the initiator of the nuclear exchange.
There are at least two scenarios where the justification for countervalue retaliation would be difficult to deny: a preemptive nuclear attack on a state’s strategic forces or a conventional invasion.55 In these scenarios, nuclear retaliation might be permissible for the reason outlined above: the more powerful side cannot dictate the terms under which its aggression can legitimately be answered. Nonetheless, no amount of sophistry can obscure the barbarism of nuclear strikes on population centers. A state retaliated against in this manner may very well escalate, especially if its leaders viewed the precipitating attack as having had limited aims. Their reaction may take the form of a grossly disproportionate counterretaliation—the fear of which constitutes a second potential source of self-deterrence.