Never Forget: Holocaust Survivors Return to Auschwitz, 70 Years Later

Survivors gather as specter of anti-Semitism still haunts Europe's Jews.

They are old. And they are the last who can testify to us about what it was like -- the darkness, the unspeakable darkness. For others, the smell of burning bodies, human smoke from the crematoriums, lingers forever in memory.

Today’s commemoration was noticeably smaller than those in previous years. Only a few world leaders came and the U.S. sent the Treasury secretary.

However, as the terror attacks in Paris and other recent anti-Semitic incidents in Europe and elsewhere have demonstrated, Jews are once again being targeted just because they are Jews.

"For a time, we thought that the hatred of Jews had finally been eradicated," Ronald Lauder, the president of the World Jewish Congress, told those assembled at today's ceremonies. "But slowly the demonization of Jews started to come back.

The Associated Press contributed to this report.