Rouhani clearly needs to have the sanctions removed as quickly as possible, and a limited deal won't accomplish that. In his meeting with the P5+1 ministers, Zarif spoke about an agreement that would be fully implemented within one year, meaning he clearly wants the sanctions to be lifted in that time. Only a more comprehensive understanding could lead to major sanctions relief and provide the administration with what it requires -- a rollback of the Iranian nuclear program that provides the United States with a high degree of confidence that the Iranians cannot cheat and produce a breakout capability at a time of their choosing.
To produce such a deal, the United States will need to be clearer with the Iranians about the threshold that it will not let their nuclear program cross. Obama has repeatedly said that an Iranian nuclear weapon threatens vital U.S. interests, as it could spur a regional nuclear arms race in the Middle East and threaten the fabric of the international nonproliferation regime. But he needs to make sure that his repeated public commitment to prevent Iran from obtaining a nuclear bomb does not lose its meaning. The pace and scope of Iran's nuclear program -- with the installation of a new generation of centrifuges and ever more accumulated enriched uranium -- create precisely such a risk in the coming months.
It is not enough for the United States to say that this line is an Iranian nuclear weapon, since this would enable Iran to develop a threshold nuclear capability that is just a few turns of the screw away from a weapon. Providing greater clarity of the point at which Iran's nuclear infrastructure would begin to threaten America's ability to fulfill its objective of prevention is important in ensuring that neither Iran nor others misjudge what would trigger an American strike.
Interestingly, Iran has already shown it is not oblivious to thresholds. It has avoided surpassing the threshold of 240 kilograms of 20 percent enriched uranium that Israeli Prime Minister Benjamin Netanyahu explicitly drew in his U.N. General Assembly speech last year.
That said, the American threshold does not need to be defined publicly. The United States should not needlessly back the Iranians or itself into a corner. However, the Iranians, the Israelis, and the other members of the P5+1 should know with greater specificity the limits of what the Obama administration will tolerate with Iran's nuclear program. As Obama just said at the United Nations in the context of the Syrian crisis, only the credible threat of force has given diplomacy a chance for success.
Moreover, the Iran issue is being viewed through the lens of the ongoing Syria crisis. Amid doubts that the U.S.-Russian deal will truly lead Damascus to completely turn over its chemical weapon stockpiles, observers in Israel and elsewhere in the Middle East have interpreted the initiative as evidence that the American public is too war-fatigued to be counted on to back a U.S. strike against Iran's nuclear program should diplomacy fail. And as long as confidence in the United States is flagging and Israel feels it is on its own, the chances of an Israeli strike increase.
Clearly, everyone should prefer a diplomatic solution with Iran. Obama's best chance to obtain that diplomatic breakthrough is through clarity -- by demonstrating to Rouhani what he can live with and what he cannot abide. Clarity will also help dispel misconceptions in the Middle East about America's resolve.
The United States should not be afraid to lift the requisite economic sanctions, if Iran comes through with its part of the bargain. The Iranian position in the talks will make it clear soon enough whether it is sincere about reaching a deal or whether Iran is only willing to make cosmetic adjustments. But in the bid to divine Rouhani's mind, we first have to know our own.