03/09/2012 05:51 pm ET Updated May 09, 2012

Which Side's Hardliners Will Sabotage US-Iran Diplomacy? Enter Romney and Lieberman

We're at a rare moment in which both the United States and Iran have unclenched their fists and appear ready for real talks.

Obama, thankfully, has taken the pro-war crowd to task. The P5+1 are finally setting new negotiations for April. And Iranian Supreme Leader Khamenei took the rare step of publicly welcoming new talks.

These are very hopeful signs that a breakthrough may be achievable. But we've seen how opportunities have been sabotaged in the past by political opportunism, ultimatums and intransigence from each side that has demanded maximalist concessions and blocked compromise necessary for diplomatic progress.

So, the question is: which side's hardliners will screw things up this time?

Enter Senators Graham (R-SC), Casey (D-PA) and Lieberman (I-CT). They recently introduced a resolution in the Senate that effectively says the U.S. will go to war if Iran acquires an undefined "capability" to build a nuclear weapon. They defended their stance in the Wall Street Journal this morning:

"Some have asked why our resolution sets the goal of preventing Iran from acquiring a "nuclear weapons capability," rather than "nuclear weapons." The reason is that all of the destabilizing consequences of a nuclear-armed Iran will ensue as soon as Iranians have the components necessary for a weapon--and by then, it will be too late to stop them.

"When some say that our red line is a "nuclear weapon," it suggests that anything short of a working bomb is acceptable. This is exactly the wrong message to send."

The Senators should ask themselves how such a demand is read in Iran. As Eugene Robinson explains in his column this morning, "The truth is that every nation with sufficient wealth and scientific infrastructure has the capacity to build a bomb if it really wants to."

Does the Lieberman-Graham-Casey trifecta really think the Iranians will capitulate to an ultimatum that demands they never achieve economic or scientific progress? How do we sell that exactly?

"The United States and its allies," writes Robinson, "should seek to eliminate the Iranian government's will to make a bomb, not its capacity."

Robinson calls out Mitt Romney for hopping on the "capability" bandwagon in an attempt to out-hawk Obama. Robinson warns that the "capability" crowd is effectively calling their own bluff:

"U.S. policy under Obama -- and previous administrations -- has been that it is "unacceptable" for Iran to have nuclear weapons. The clear implication is that, while military force is an option that could be employed at any time, including the present, force will be employed if Iran tries to make a bomb.

"To say that Iran must never have "the capacity to make a bomb," as Romney does, is to draw a line that has already been crossed."

Though they still haven't explained what they really think "capability" means, presumably the Senators define preventing "capability" as getting Iran to forgo even a verifiably peaceful nuclear enrichment program and to waive its rights under the Nuclear Nonproliferation Treaty. This is the precondition that the Bush Administration adopted, which yielded nothing but Iranian nuclear advances throughout his term.

Yes--a world in which Iran decides it doesn't want any nuclear enrichment program at all would be great. But it is certainly not a vital goal, nor is it a realistic one. We certainly shouldn't make it our ultimatum so that it blocks opportunities to achieve our real goal--preventing Iran from actually building a bomb.

This is an important example of the perfect becoming the enemy of the good. Military strikes on Iran would not stop Iran's nuclear program and would be a disaster for Iran's pro-democracy and human rights movement. But there are safeguard measures and mechanisms that can be implemented through negotiations and which can achieve our real goals. We shouldn't let non-essential demands get in the way. Otherwise, the opportunity for a peaceful breakthrough will be scuttled yet again and the pressure for war may well reach its breaking point.

Email your elected officials to stop the Lieberman-Graham-Casey "capability" resolution