Obama’s commitment to rapprochement with Iran arises from deep personal identification with the supposed victims of imperialism. That is incongruous, to be sure. Persia spent most of its history as one of the nastier imperial powers, and its present rulers are no less ambitious in their pursuit of a pocket empire in the Shi’ite world. The roots of his policy transcend rationality. Israel can present all the evidence in the world of Iran’s plans to build nuclear weapons and delivery systems, and the Iranians can cut the Geneva accord into confetti. Obama will remain unmoved. His heart, like his late mother’s, beats for the putatively oppressed peoples of the so-called Third World.

No factor of this sort was present in 1938: Neville Chamberlain did not sympathize with Hitler. He simply feared him and needed time to rearm, as the Wall Street Journal’s Mr. Stephens observes. If Lord Halifax rather than Chamberlain had been prime minister then, the parallel to Obama would be stronger.

I do not know how Israel will respond. There are too many unknowns in the shifting political equation of the Middle East to solve that equation. But the facts on the ground support the Israeli view that the Geneva accord puts the Jewish State at existential risk.