JOEL KOTKIN: Delusions of Justice: American Jews should wake up to which side their most dangerous enemies are on.

Since the election of Donald Trump, prominent American Jews, notably in the Reform movement and among the intelligentsia, have lamented the resurgence of right-wing anti-Semitism, seeing it as the greatest threat to their community in the United States. The rise of xenophobic and often marginally anti-Jewish parties in Eastern Europe—even with fewer Jews left there to persecute—has deepened the alarm. Yet by far the greatest threat to Jews, not only here but also abroad, comes not from zombie fascist retreads, but from the Left, which is increasingly making its peace with anti-Semitism.

This shift was first made clear to me about 15 years ago when, along with my wife Mandy, whose mother was a Holocaust survivor from France, I visited the legendary Nazi-hunters Serge and Beate Klarsfeld. They predicted that the primary threat to Jews in Europe increasingly would come not from the centuries-old French Right, some of whom had supported the Nazis, but from the Left, in alliance with a growing Muslim population. Time has proved their assertion to be, for the most part, on target. In Sweden, for instance, never known for its persecution of Jews, only 5 percent of all anti-Semitic incidents, notes the New York Times, involved the far Right, while Muslims and leftists accounted for the rest. Germany’s recent rash of anti-Semitic incidents has coincided with the mass migration of people from regions where hostility to both Jews and Israel is commonplace. At European universities, where pro-Nazi sentiments were once widely shared, anti-Israel sentiments are increasingly de rigueur. The growing Boycott, Divestment and Sanctions (BDS) movement, aimed at cutting all ties with Israel, often allies itself with anti-Jewish Islamist groups, some with eliminationist agendas for Palestine’s Jews.

Many politically active Jews, though, see themselves as leftists first, and Jews second.