Pollack believes that, were it not for Israel “repeatedly sounding the alarm,” Iran “probably would have crossed the nuclear threshold long ago.” But if a nuclear Iran is for Israel unthinkable because it is uncontainable, Israel’s only self-reliant recourse — a nuclear attack on Iran’s nuclear infrastructure — is unthinkable. And, Pollack thinks, unnecessary. The existence of Israel’s nuclear arsenal is a sufficient deterrent: The Iranian leadership is “aggressive, anti-American, anti-status quo, anti-Semitic, duplicitous, and murderous, but it is not irrational, and overall, it is not imprudent.”

There will be no constitutional impropriety if Congress recoils against the easing of sanctions and votes to impose even stiffer ones on Iran. The president has primary but not exclusive responsibility for foreign policy. It is time for a debate about the role of sanctions in a containment policy whose ultimate objective is regime change. For many decades prior to 1989, humanity was haunted by the possibility that facets of modernity — bureaucracy and propaganda technologies — could produce permanent tyrannies impervious to change. (See Hannah Arendt’s “The Origins of Totalitarianism.”) In “Nineteen Eighty-Four,” George Orwell wrote, “If you want a picture of the future, imagine a boot stamping on a human face — for ever.” Since 1989, however, tyrannies seem more brittle. And Pollack believes “the basic ingredients of regime change exist in Iran,” which “today is a land of labor protests and political demonstrations.”

Pollack may be too sanguine when he says that, since the brutal smashing of the Green Revolution of June 2009, “the Islamic Republic has been delegitimized and is starting to hollow out.” His fear is that even massive U.S. air strikes would only delay the danger that provoked them and thus might “prove to be nothing more than a prelude to invasion, as they were in Iraq and almost were in Kosovo.”