Russia’s 2014 annexation of Ukraine’s Crimea peninsula ignited the tensest standoff between Moscow and the West since the Cold War. The region remains deadlocked, following years of conflict between Ukraine and Russian-backed separatists in the country’s east. Since November, the U.S. has been warning European allies that Russia may be preparing to invade Ukraine, already massing 100,000 troops near its neighbor’s border in a re-run of a crisis in April 2021.