There has been widespread discussion of Russia’s threat to use tactical nuclear weapons in its war on Ukraine. Russia is estimated to have thousands of tactical nuclear weapons—possibly the world’s largest stockpile—which could be deployed at any time. The use of nuclear weapons is also embedded in Russian military doctrine. Ukrainian President Volodymyr Zelenskyy has appealed to the rest of the world to take the threat seriously. In this article we examine what… – Phys.org Photo: CC BY-SA 4.0 / Boevaya mashina