The 12th Main Directorate, responsible for Russia’s nuclear arsenal, is a secretive organization, making it difficult to know much about their plans. However, it’s believed that in the event of a crisis, they would move nuclear weapons from central storage bases to base-level storage sites. Convoys of trucks with security guards would transport these weapons, but it’s uncertain whether this is happening.

Ukraine is a large war zone, with many potential military targets, but Russia’s tactical nuclear weapons are unlikely to be effective against these dispersed units. According to a US plan from 1977, it would take 136 nuclear detonations to stop an advancing Soviet force along a 100km front, which is roughly 20 times the size of the current front in Ukraine. Russia likely has between 1,500 to 2,000 tactical nuclear weapons, but it’s unclear how effective they would be in this situation.

Russian weapon testing is also a concern, as they have not conducted a nuclear test in over 30 years. The US has not conducted a nuclear test in over 30 years as well, and even if Russian warheads are assumed to be half as effective, they would still pose a threat. Radiation is another factor to consider, as smaller nuclear warheads tend to cause less radiation than larger ones.

If Russia were to use nuclear weapons, it’s unclear how the West would respond. Some officials have suggested a kinetic response, while others have suggested a more measured approach, potentially sending long-range and more powerful weapons to Ukraine. Ultimately, the probability of Russia using nuclear weapons is low, with estimates ranging from 10 to 20%. The impact of such an event would be significant, but the devastating effects would be largely psychological rather than physical.