In 1938, British Prime Minister Neville Chamberlain described the escalating conflict between Nazi Germany and Czechoslovakia as "a quarrel in a faraway country between people of whom we know nothing." Less than two years later, Nazi bombs fell on London. More than eight decades have passed since then, and while Russia's unprovoked war in Ukraine is far from a perfect comparison to Nazi Germany's attack on Czechoslovakia, it bears striking similarities. A powerful authoritarian government launched a war over bogus territorial disputes and false claims of genocide. Its soldiers are perpetrating war crimes. And democracies worldwide are faced with a...