Biden Must Counter Putin’s Ukraine Threat

By all indications, Russia is preparing a winter assault on parts of Ukraine that it left untouched when it annexed the Crimean peninsula and launched a hybrid-warfare campaign against the Eastern Donbas region.

Vladimir Putin and his ideological allies have spent the past several months making the case for absorbing Ukraine. Per the head of Ukraine’s defense-intelligence service, Moscow had, as of mid November, placed some 92,000 troops on its border with Ukraine. That’s fewer than the over 100,000 soldiers it moved there during a similar buildup in the spring, but...