Russia’s assault on Ukraine and its veiled threats of using nuclear arms have policymakers, past and present, thinking the unthinkable: How should the West 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. That could entail stepping up sanctions and isolation for Russian President Vladimir Putin, said Rose Gottemoeller, deputy secretary-general… – Detroit News Photo: Sputnik / Sergei Guneyev