The military standoff between Russia and Ukraine is escalating as Jews in both countries prepare to commemorate International Holocaust Remembrance Day on Jan. 27, the day that Soviet troops liberated Auschwitz in 1945. The coincidence is an annual reminder of the complicated legacy shared by Russia and many countries in its orbit. But to some Ukrainian Jews, it’s also a mental note to stay vigilant, plan for the worst — and prepare to move fast out of harm’s way amid growing fears of an invasion by the hundreds of thousands of Russian troops that President Vladimir Putin has amassed in...