Here are a couple of things to keep in mind when evaluating the deal negotiated by Brazilian President Luiz Inacio Lula da Silva and Turkish Prime Minister Recep Tayyip Erdogan for Iran to ship much of its low-enriched uranium to Turkey. On the one hand, the Obama administration is committed to multilateral diplomacy, and Brazil and Turkey are partners on the U.N. Security Council with, presumably, no more interest in a nuclear-armed Iran than the U.S. and Western Europe; they should be regarded as honest brokers. On the other hand, Iran is a master of the long game, repeatedly tendering offers in tactical moves to stave off economic sanctions while buying time to advance its nuclear technology. And this latest deal clearly throws a wrench into the sanctions efforts — at least for now.

The proposal includes concessions from Tehran, which had been reluctant to ship its uranium abroad. Now, Iran says it would ship 2,600 pounds of reactor-grade uranium to Turkey, a Muslim country, where it would be jointly monitored by Iran and the International Atomic Energy Agency for up to a year. In return, Iran would receive higher-enriched nuclear fuel plates to be used in a reactor for medical research purposes. A previous proposal in October for Iran to send its low-enriched uranium to Russia for refinement and then onto France collapsed in part because Iran feared a double-cross and wanted the exchange to be simultaneous.

Serious problems remain, however. When originally proposed last year, the exchange was to have been a confidence-building measure to reduce Iran's stockpile of enriched uranium by about 70%, to below the level necessary to make a bomb, thereby giving Tehran and the West time to negotiate a broad deal for Iran to pursue nuclear energy while ensuring it could not develop a nuclear bomb. But Tehran has continued to enrich uranium in the last seven months, and the IAEA estimates that it may now be offering to give up only 50%, leaving it with enough to build a bomb anyway. Moreover, Iran has recently begun enriching uranium to a higher level and says it will continue to do so in what the White House called a direct violation of Security Council resolutions.

We don't want to dismiss the effort by Brazil and Turkey to mediate a solution, particularly if they can bring Iran and the U.S. to the negotiating table. But the Obama administration is right to remain skeptical, given what it called "Iran's repeated failure to live up to its own commitments." The goal is not a short-term swap of nuclear fuel but a long-term agreement on Iran's nuclear program. And there's nothing in the proposal crafted by Brazil and Turkey that commits Iran to resolving the bigger issues.