A damaged gas mask lies on the pavement at a Russian position which was overran by Ukrainian forces, outside Kyiv, Ukraine, March 31, 2022. Russia’s assault on Ukraine and its veiled threats of using nuclear arms have policymakers questioning how the West should respond to a Russian battlefield explosion of a nuclear bomb. The default U.S. policy answer, say some architects of the post-Cold War nuclear order, is with discipline and restraint. (AP Photo/Vadim Ghirda, File)
