The White House struggled to portray the estimate as a validation of Mr. Bush’s strategy, a contention that required swimming against the tide of Mr. Bush’s and Mr. Cheney’s occasionally apocalyptic language.

The national security adviser, Stephen J. Hadley, said the estimate showed that suspicions about Iran’s intentions were warranted, given that it had a weapons program in the first place.

“On balance, the estimate is good news,” Mr. Hadley said, appearing at the White House. “On one hand, it confirms that we were right to be worried about Iran seeking to develop nuclear weapons. On the other hand, it tells us that we have made some progress in trying to ensure that that does not happen. But it also tells us that the risk of Iran acquiring a nuclear weapon remains a very serious problem.”

Mr. Hadley insisted, as he and others have, that the administration had hoped and still hoped to resolve the outstanding questions about Iran’s nuclear programs using diplomacy, not force. But the nuances of his on-this-hand-on-the-other argument will probably make it much harder to persuade American allies to accept the administration’s harder line.

One official pointed out that the chief American diplomat on the Iran question, Under Secretary of State R. Nicholas Burns, had just met with counterparts from Europe, Russia and China, and had seemed to make some headway on winning support for a third round of sanctions by the United Nations Security Council. The official said Mr. Burns could not divulge the intelligence findings at that meeting on Friday because Congress had not been briefed.

The immediate task for Mr. Burns and other administration officials is to untangle the confusion caused by its own statements and findings and to persuade skeptics that this time, the United States has it right about what Iran was doing before 2003 and what that means for what it might do in the future.