For instance, the RUSI report says use of a tactical nuke in the Sulwaki Gap, the land border between NATO allies Poland and Lithuania that separates Russian Kaliningrad from its neighbor Belarus, could only cause civilian casualties in the hundreds.

The reality is likely to be far from that.

“US war games predict that a conflict involving use of tactical nuclear weapons will quickly spiral out of control,” the Union of Concerned Scientists blog said.

“A Princeton University simulation of a US-Russian conflict that begins with the use of a tactical nuclear weapon predicts rapid escalation that would leave more than 90 million people dead and injured,” it said.

Responding to Putin’s threat last week, the International Campaign to Abolish Nuclear Weapons (ICAN) says the Europe of 2022 is a much more dangerous place to use nuclear arms than the Japan of 1945, which had a smaller population and was relatively isolated.

In Europe today, “a single nuclear detonation would likely kill hundreds of thousands of civilians and injure many more; radioactive fallout could contaminate large areas across multiple countries,” ICAN said on its website.

“Emergency services would not be able to respond effectively and widespread panic would trigger mass movements of people and severe economic disruption. Multiple detonations would of course be much worse,” it added.