Paul Pillar explains why the new Israel/Iran resolution sponsored by Sens. Lindsey Graham and Robert Menendez is so foolish and harmful to negotiations:

With this situation of discernible but reversible progress at the negotiating table, the worst thing that anyone—especially anyone who supposedly favors restricting Iran’s nuclear program to preclude an Iranian nuclear weapon—could do at this moment would be anything that stokes the Iranian suspicions about true U.S. intentions. But that is what is being done right now in Congress, with two draft measures in particular. One is a bill—a kind that members by now could write in their sleep—to pile still more sanctions on Iran. Probably even worse is a Senate resolution introduced by Lindsey Graham and Robert Menendez that for most part is just another expression of Congressional love for Israel but that ends with a clause that gives a green light for Israel to launch a war against Iran.

The text of the resolution calls for U.S. support, including military support, in the event that Israel is “compelled to take military action in self-defense.” That might sound innocuous enough if the rest of the resolution weren’t filled with justifications for preventive war against Iran. Of course, our own government reserves the right to engage in so-called “anticipatory self-defense” (i.e., starting wars without provocation), so it’s no wonder that Iran hawks would want to affirm U.S. support for Israel to do the same. The most delusional part of the resolution comes at the end when it refers to U.S. support for Israel’s defense of its “existence,” which relies on the false and alarmist notion that there is currently any external force could and would seriously threaten Israel’s existence. The resolution isn’t binding, and it doesn’t require the administration to do anything, but it’s exactly the sort of “signal” that is very likely to be interpreted in Tehran as evidence of implacable U.S. hostility. If one wanted to sabotage even modest progress in negotiations, this is the sort of resolution one would sponsor.

Pillar continues:

That latter resolution would be extraordinarily inappropriate even if it came at a less promising and critical time—a “turning point,” according to Jalili—than now. The resolution condones what would be an act of aggression that, despite supposedly being taken in the name of nuclear nonproliferation, would be committed by a state that has long had an arsenal of nuclear weapons that is totally outside any international control regime, against a state that has no such weapons and hasn’t even decided it wants to build any. The resolution also means happily surrendering to a foreign state the decision to start a war that would have serious repercussions for the United States.

This is what makes the resolution and the endorsement of preventive war implicit in it so perverse. It is bad enough to describe illegal aggression as self-defense, but even if one agreed with preventive war in principle there is no good reason to wage it against Iran. These threats of military action undermine negotiations, but more important they make proliferation and Iran’s eventual withdrawal from the NPT more likely.