The Wall Street Journal editors ask a silly question:

President Obama says he won’t sign a deal with Iran that fails to stop its nuclear weapons program. So why is he threatening to veto a Senate sanctions bill that would strengthen his hand in negotiations with Tehran?

They know the answer to this question as well as anyone else, but it doesn’t interest them. It should be clear enough that additional sanctions or even the threat of additional future sanctions risks derailing negotiations. If Iran didn’t honor its part of the interim or final agreement, the sanctions that have been lifted could be restored, but to threaten a new set of even more severe sanctions before the interim deal has had a chance to lead anywhere gives Iran reason to assume that the U.S. has been acting in bad faith all along. The rest of the bill would give Iran other reasons to assume this. Gary Sick (via Scott McConnell) points out that the bill sets an impossible goal for the final agreement:

Instead, it insists on the objective defined by Prime Minister Netanyahu, among others, to eliminate all capability by Iran to ever build a nuclear device. As I’m sure you [Schumer] know, even the most peaceful nuclear activity can be used for military purposes. It is possible to regulate how far a country is away from a nuclear weapon. It is not possible to eliminate the possibility entirely.

In addition to setting an unreasonable goal for a final deal, the bill endorses an Israeli attack on Iran and asserts that the U.S. should support that attack. The text reads:

if the Government of Israel is compelled to take military action in legitimate self-defense against Iran’s nuclear weapon program, the United States Government should stand with Israel and provide, in accordance with the law of the United States and the constitutional responsibility of Congress to au-thorize the use of military force, diplomatic, military, and economic support to the Government of Israel in its defense of its territory, people, and existence.

It can’t be stressed often enough that an illegal and unauthorized attack on Iran would have nothing to do with “legitimate self-defense.” So-called preventive war cannot ever really be waged in self-defense. No state is compelled to wage preventive war. It is a perfect example of an unnecessary and avoidable war. Regardless, Iran wouldn’t perceive an unprovoked attack on its territory by another state as legitimate or an act of self-defense, but as unwarranted aggression. If Congress passed this bill, and Obama signed it, they would be telling Iran that there was no point in pursuing a negotiated deal with the U.S. and the other members of the P5+1, because the U.S. would have already confirmed publicly that it has no problem with an Israeli attack on their country. Obama is right to threaten to veto the legislation, since signing it would be the equivalent of sabotaging his administration’s own diplomatic efforts.