AP Photo

The writer Ron Rosenbaum, in an essay for Slate that I mentioned last week, asks the question: How much discussion about the Holocaust is too much? Why does he raise this now? Because we’re approaching a pivotal moment in the continuing drama surrounding Iran’s nuclear progress -- and that means the U.S. may once again find itself in a position to confront the threat of genocide.

The rulers of Iran, who deny the historical reality of the Holocaust even as they dream of annihilating Israel, may in the very near future possess the ability to build nuclear weapons and to immunize their nuclear program from outside intervention. Rosenbaum argues eloquently that it isn’t neurotic or hysterical or parochial to worry that a regime that seeks the annihilation of Israel may...