Full credit for this debacle goes to the Obama Administration and its hapless diplomatic strategy. Last October, nine months into its engagement with Tehran, the White House concocted a plan to transfer some of Iran’s uranium stock abroad for enrichment. If the West couldn’t stop Iran’s program, the thinking was that maybe this scheme would delay it. The Iranians played coy, then refused to accept the offer.

But Mr. Obama doesn’t take no for an answer from rogue regimes, and so he kept the offer on the table. As the U.S. finally seemed ready to go to the U.N. Security Council for more sanctions, the Iranians chose yesterday to accept the deal on their own limited terms while enlisting the Brazilians and Turks as enablers and political shields. “Diplomacy emerged victorious today,” declared Brazil’s President Luiz Inácio Lula da Silva, turning Mr. Obama’s own most important foreign-policy principle against him…

So instead of the U.S. and Europe backing Iran into a corner this spring, Mr. Ahmadinejad has backed Mr. Obama into one. America’s discomfort is obvious. In its statement yesterday, the White House strained to “acknowledge the efforts” by Turkey and Brazil while noting “Iran’s repeated failure to live up to its own commitments.” The White House also sought to point out differences between yesterday’s pact and the original October agreements on uranium transfers.

Good luck drawing those distinctions with the Chinese or Russians, who will now be less likely to agree even to weak sanctions.