Much of strategic deterrence (the formal term for nuclear deterrence) is analyzed and approached through game theory. So much so that the US DoD's entire strate

Much of strategic deterrence (the formal term for nuclear deterrence) is analyzed and approached through game theory. So much so that the US DoD's entire strategy rests on 1 simple assumption: "Every operational plan in the DoD, and every other capability we have, rests on the assumption that strategic deterrence, and in particular nuclear deterrence, will hold. If strategic or nuclear deterrence fails, integrated deterrence and no other plan or capability in the DoD will work as designed. The Nation’s nuclear forces underpin integrated deterrence and enable the U.S., our Allies and partners to prevent and, if necessary, confront aggression around the globe using all instruments of national power" Source: https://www.stratcom.mil/Portals/8/Documents/2022%20USSTRATCOM%20Posture%20Statement.pdf?ver=CUIoOCLyos9xe9C9I0XjMQ%3D%3D https://www.stratcom.mil/Portals/8/Documents/2022%20USSTRATC... The threat of Russia's deployment of non-treaty tactical weapons on a non-NATO state has been carefully analyzed for a long time: https://sgp.fas.org/crs/nuke/RL32572.pdf https://sgp.fas.org/crs/nuke/RL32572.pdf The most credible reason for Russia to commit to such a deployment of weapons is if Russia believed that the deployment would ultimately lead to a de-escalation of a conflict ("escalate to de-escalate"). At this point, the US/NATO has made clear publicly that any escalation to WMDs/strategic weapons will lead to a response in kind. A response in kind would not lead to de-escalation, and thus Russia's threat isn't really credible other than for information warfare purposes. But of course, much of game theory rests on the assumption of common knowledge of rationality. This is why the diplomatic/intelligence establishment is so concerned with the state of Putin's rationality.