But what is happening here is something virtually without precedent in our allegedly enlightened age: A member-state of the United Nations, Iran, regularly threatens another member-state, Israel, with annihilation. It’s important to bear in mind a fundamental asymmetry: Israel doesn’t seek Iran’s elimination. Iran seeks Israel’s.

Regime apologists will note that Iranian leaders talk about the elimination not of “Israel” -- a word they generally refuse to utter -- but of the “Zionist regime,” which, to the naive and the cynical, implies the replacement of one government with another. This is a pernicious euphemism. Without the “Zionist regime” -- which is to say, the democratically elected government of Israel, its armed forces and security services, and the courts and structures of state -- the Jews who survived the onslaught that “dismantled” their government would face immediate dispossession, and perhaps much worse.

Rosenbaum, an expert on Hitlerian euphemism, told me that one difference between Nazi rhetoric and that of the Iranian regime is that the Iranians’ words are blunter, especially when compared with pre-Kristallnacht Nazi language. Rosenbaum notes, in particular, the Iranian reliance on epidemiological metaphor when describing Israel: This year, the Iranian supreme leader,Ayatollah Ali Khamenei, said Israel is “a true cancer tumor on this region that should be cut off.”

Which returns us to Rosenbaum’s central question: Is it obsessive for a group of people who not long ago saw a third of their number slaughtered to worry when the leaders of Iran call Israel a cancerous tumor? Or is it the natural and appropriate response of a people who, conditioned by history, choose to err on the side of caution?