There is little doubt that there was an open Iranian attitude in 2003 and in the immediate period thereafter, but U.S. policy at the time barred exploration of the possibilities. There is little doubt that infighting in Iran after the 2009 election blocked its acceptance of a generous and constructive offer related to its research reactor. And there is, in our opinion, little doubt that we would be in a better position now had we further explored the diplomatic opening made by Turkey and Brazil in the spring of 2010.

But now diplomacy is to be given a new chance after nearly two years of inaction. This time, we should aim for a sustained diplomatic engagement that seeks to build trust through a series of steps, as bridging the immense gulf of mistrust will not be done in a day.

Iran has its rights under the Nuclear Nonproliferation Treaty, but it also has its obligations. And it must understand that its behavior has created misgivings about its intentions. In its own interest, Iran should consider steps that could start to remedy that situation.

From 2003 to the beginning of 2006 Iran voluntarily applied the Additional Protocol, with its more comprehensive and intrusive inspection arrangement, and few steps would be more important in building confidence than Iran going back to abiding by this protocol. Indeed, this inspection regime, as well as full cooperation with the International Atomic Energy Agency, is key to any agreement between Iran and the international community on the nuclear issue.

Moreover, it now seems that Iran will have soon completed enriching uranium to 20 percent, which it says it needs for its research reactor. It would make sense to then suspend these activities. New research reactors will take a long time to build, so international safeguards for them could be put in place.