Russia’s president, Vladimir V. Putin, and his government have been deft at using the history of Ukrainian anti-Semitism to their advantage. At his first news conference after moving his troops into Crimea, Mr. Putin described right-wing fanatics in Kiev wearing armbands with swastikalike symbols, warning that, in upcoming elections, “like a Jack-in-the-box, some nationalist-type or semifascist element ... or some kind of anti-Semite could pop out.”

His foreign minister, Sergei V. Lavrov, has repeatedly tried to discredit the revolution that toppled Ukraine’s pro-Russian president last month by calling it a “pogrom.” The Russian ambassador to the United Nations, Vitaly I. Churkin, likened the demonstrators to the Ukrainian fascists who collaborated with the Nazis against the Soviet Union during World War II.

This is more than merely a cynical ploy. In invoking Ukraine’s history of anti-Semitism, Mr. Putin and his deputies are not so much trying to appeal to the at least 70,000 Jews there today as to the millions of Russian speakers (many Jews among them) who have watched with ambivalence the toppling of statues of Lenin — still a symbol for older Ukrainians of the triumph of communist internationalism over Nazism. They are also proposing a high-stakes bet: If the true fascist nature of Ukraine’s new leaders emerges, naïve Westerners, including President Obama, will find themselves on the wrong side of history....