But, at least in the short term, negotiations remain the best way to stop Iran from crossing the nuclear threshold. And U.S. President Barack Obama cannot be hamstrung in discussions by a group of senators who will pay no price for causing the collapse of negotiations between Iran and the P5 + 1, the five permanent members of the security council, plus Germany. “You have a large group of senators who are completely discounting the views of the administration, the actual negotiators, the rest of the P5 + 1, the intelligence community and almost every Iran analyst on earth,” said Colin Kahl, who, as a deputy assistant secretary of defense for the Middle East during Obama’s first term, was responsible for preparing all of the options that the President says are still on the table.

If these negotiations were to collapse — and collapsing the negotiations is the goal of some of the most hawkish hawks — the most plausible alternative left to stop Iran would be a preventative military strike, either by the U.S. or by Israel (Arab states, which are agitating for an American strike, wouldn’t dare take on the risk of attacking Iran themselves). Such a strike might end in disaster. While it could set back (though not destroy) Iran’s nuclear program, it could also lead to the complete collapse of whatever sanctions remained in place. In addition, it could unify the Iranian people behind their country’s unelected leader, Ayatollah Ali Khamenei — a particularly perverse outcome. And in some ways, an attack would justify Iran’s paranoia and pursuit of nuclear weapons: After all, the regime could somewhat plausibly argue, post-attack, that it needs to defend itself against further aggression. A military campaign should be considered only when everything else has failed, and Iran is at the very cusp of gaining a deliverable nuclear weapon.