Regret is what Ukrainian leaders must be feeling these days, as Russia amasses troops along the border. There’s nothing that says “keep your hands off my territory” like fully armed, nuclear-tipped weaponry — the sort that Kyiv surrendered shortly after the Soviet Union collapsed in 1991. Now officials have no nuclear option to deter an invasion.

The international community should be careful how it lets this play out. Nations that still have access to weapons of mass destruction will draw conclusions about whether to cling to those armaments at all costs. READ MORE