ATLANTA — AN old Jewish joke goes like this: “What’s the definition of a Jewish telegram? ‘Start worrying. Details to follow.’ ”

I am often asked by fellow Jews about contemporary manifestations of anti-Semitism, particularly in Europe. “Is this just like 1939? Are we on the cusp of another Holocaust?” Until now, my answer has been an unequivocal “no.” I have criticized community leaders who, either out of genuine concern or to advance their own purposes, use Holocaust analogies to describe contemporary conditions. These claims are ahistorical. They overstate what is going on now and completely understate the situation in 1939.

The differences between then and now are legion. When there is an outbreak of anti-Semitism today, officials condemn it. This is light-years away from the 1930s and 1940s, when governments were not only silent but complicit. Memory also distinguishes the present from previous events. Now, in contrast to the 1930s, we know matters can escalate. Jews today are resolute in their determination: “Never again.”

And despite all this I wonder if I am too sanguine. Last month, pro-Gaza protesters on Kurfürstendamm, the legendary avenue in Berlin, chanted, “Jews, Jews, cowardly swine.” Demonstrators in Dortmund and Frankfurt chanted, “Hamas, Hamas; Jews to the gas!” And a pro-Hamas marcher in Berlin broke away from the crowd and assaulted an older man who was quietly standing on a corner holding an Israeli flag.