President Vladimir Putin has chosen the path of destruction instead of diplomacy. The Kremlin’s war on Ukrainian cities, towns, nuclear power stations, hospitals, and civilians is indefensible, illegal, premeditated, and heartbreaking. Making matters worse, Putin’s nuclear saber-rattling is raising the risk of escalation in ways we have not seen since the end of the Cold War. If NATO and Russian military forces become entangled in the fight, the war could widen further and could potentially move to the nuclear level–with catastrophic consequences. Since Putin’s decision to invade Ukraine, our...