UNITED NATIONS — Brazil and Turkey managed to fracture the Security Council today, throwing President Obama’s Iran strategy into limbo.

Even if the Turtle Bay top body ends up eking out a resolution that would impose a new round of sanctions on Iran this spring, the deal that Brazil, Turkey, and Iran announced today will surely sow enough discord among the members of the Security Council that Tehran could justifiably declare that such sanctions lack the full backing of the so-called “international community.” So it adds up for a defeat for Mr. Obama, who has sought for months to unite the council behind his Iran policy.

Several Western diplomats familiar with negotiations that have been held for months among the five Security Council powers said that in closed-door consultations in New York today, China’s initial response to the Monday Tehran deal was “positive” from the West’s point of view. Only hours after the deal was announced this morning at Tehran, the ambassadors of the five permanent members of the Security Council and Germany convened in a previously-scheduled meeting at New York. According to the Western diplomats, Beijing indicated in the closed-door parley it would not renege on past agreements the group has already reached. In effect, China thus declined, at least initially, to endorse the Tehran deal.

Even if Beijing, which has not yet commented officially on the Tehran deal, does not split with the West, it is unclear how the Obama administration, which has long vowed to heal America’s relations with the rest of the world, could declare victory, though administration officials indicated today that America would maintain its drive to get the Security Council to impose sanctions on Iran, which have emerged as one of Mr. Obama’s top international objectives.

But since two council members, Brazil and Turkey, have staked their diplomatic prestige on the Tehran deal, Washington is now unlikely to unite the entire body behind its proposed sanctions package. By contrast, the Bush administration, which was frequently accused of unilateral approach to international relations, twice succeeded in uniting all the 15-members of the Security Council behind sanctions on Iran. It also easily passed one additional near-unanimous Iran sanctions resolution, where only Qatar abstained.

Beside Turkey and Brazil at least one more country — Lebanon — is so closely-tied to Iran that it is unlikely to support any resolution that would tighten the council’s past sanctions. At least nine of the 15 council members must support any resolution before it is even voted on, and for a measure to pass, it must avoid a veto by any of the five permanent members. If Turkey, Brazil, and Lebanon indicate their opposition, other elected council members — Uganda, Nigeria, and even Bosnia Herzegovina, which has a majority Muslim population — may decline to support it as well.

Before the Monday announcement at Tehran, White House sources and Security Council diplomats were telling reporters that the five permanent council members who were negotiating the American sanctions package were close to a deal that would unite all of them behind new sanctions.

But since specific new punitive measures emerged in February, none of the 10 elected council members saw that American-proposed sanctions package. America maintained exclusive and secretive consultations with the five permanent members, at times in one-on-one sessions with China. At the same time ample warning signs showed that Brazil and Turkey, both of which aspire for regional and international leadership, were cooking up a deal that might scuttle the sanctions drive.

This morning Presidents Lula of Brazil, Erdogan of Turkey and Ahmadinejad of Iran stood in front of cameras in Tehran, announcing a uranium swap deal that replicated an agreement proposed by the International Atomic Energy Agency last year. Iran had indicated at the time that it would accept the deal, but it then reversed itself.

Today’s agreement to enrich uranium for Iran on Turkish soil was met with skepticism in Western capitals. Paris, London and Washington said that the few details that have emerged would not satisfy past Security Council demands. “Iran said today that it would continue its 20% enrichment, which is a direct violation of Security Council resolutions,” the White House Press Secretary, Robert Gibbs, said in a statement at noon. Similar concerns were expressed by President Medvedev of Russia.

Several diplomats said Iran did not aim to convince Western skeptics of its intentions. Instead, they said, the idea was to give enough cover for China, which has initially been skeptical about sanctions, to further dilute the American proposal – or kill it altogether. As of Monday evening, Beijing declined to officially comment on the proposed deal.