Published: December 4, 2007 WASHINGTON, Dec. 4 President Bush warned today that Iran remained a threat despite an intelligence assessment that it had halted a covert program to develop nuclear weapons four years ago, as the administration struggled to salvage a diplomatic process now in disarray. Skip to next paragraph Enlarge This Image Stephen Crowley/The New York Times President Bush at a press conference at the White House today. Multimedia The Intelligence, Then and NowGraphic The Intelligence, Then and Now A Question of PurposeGraphic A Question of Purpose Related U.S. Finds Iran Halted Its Nuclear Arms Effort in 2003 (December 4, 2007) News Analysis: An Assessment Jars a Foreign Policy Debate About Iran (December 4, 2007) How Did a 2005 Estimate Go Awry? (December 4, 2007) Europeans See Murkier Case for Sanctions (December 4, 2007) Candidates Hold to Their Stances on Iran (December 4, 2007) Once again facing criticism over the handling and meaning of intelligence reports, Mr. Bush said the new assessment underscored the need to intensify international efforts to prevent Iran from acquiring a nuclear weapon. He said Iran could not be entrusted with acquiring even the scientific knowledge to enrich uranium for peaceful civilian use, explicitly declaring for the first time what has been an underlying premise of the Bush administrations policy. He also appeared to rule out any new diplomatic initiative with the current president of Iran, Mahmoud Ahmadinejad. Look, Iran was dangerous, Iran is dangerous, and Iran will be dangerous, if they have the knowledge necessary to make a nuclear weapon, Mr. Bush said, sounding defensive at times, during a news conference dominated by questions about the assessment, known as a National Intelligence Estimate. Whats to say they couldnt start another covert nuclear weapons program? The assessment reversed one in 2005 that asserted that Iran was determined to develop nuclear weapons, with American intelligence agencies now saying that they do not know whether Iran intends to take that step. Mr. Bush said that the reversal was based on a great discovery by American intelligence agencies, but neither he nor other officials would elaborate. Current and former American and foreign officials said the new findings were based on intercepted communications and accounts provided by individuals with access to information about Irans nuclear program. Representative Jane Harman, a Democrat of California, said that she read the classified version of the report today and described the intelligence agencies work a sea change from the 2005 assessment in the quality of its analysis and presentation of facts. Asked about the basis for the new findings, she said: I think we have some better sourcing. Thats all I can say. Mr. Bushs remarks did little to silence critics, who have accused him of hyping the case for confronting Iran. Nor did it ease they concerns of some allies. Senator Lindsey Graham of South Carolina, a Republican, said he was perplexed by the new assessment and suspicious of the new evidence. We should all look under the hood of these intelligence reports, he said. Mr. Bush and his senior aides spent the day trying to hold together the already-fragile coalition of world powers seeking to rein in Irans nuclear ambitions. Mr. Bush telephoned President Vladimir V. Putin of Russia, who has voiced skepticism about an aggressive American effort to punish and isolate Iran. Secretary of State Condoleezza Rice also telephoned her counterparts from the five other countries that have been pursuing United Nations sanctions against Iran to urge that they continue work on a new round of increasingly tighter sanctions. This report is not an O.K., everybody needs to relax and quit report, Mr. Bush said. This is a report that says what has happened in the past could be repeated and that the policies used to cause the regime to halt are effective policies. And lets keep them up. Lets continue to work together. There were already signs that this effort had been complicated by the new report. R. Nicholas Burns, the under secretary of state for political affairs, held a conference call this morning with his counterparts from the five countries France, Germany, China, Britain and Russia. One European diplomat described the conference call as listless. Were all flabbergasted, the diplomat said of the report generally. You get such a surprise, and then you sit together and consider how to move forward. To be on safe ground, we decided to keep moving forward with the effort to press for further sanctions. A senior Bush administration official said the intelligence assessment on Iran was a setback in the effort to persuade China to endorse a new round of sanctions at the United Nations Security Council. While there had been indications over the weekend that the Chinese might drop their opposition to such a move, it appeared today that they were reconsidering again, the official said. The new intelligence assessment, the official said, gives the Chinese an opportunity to get off the hook. Mr. Bush opened himself to new criticism over his credibility when he said that the director of national intelligence, Mike McConnell, alerted him about new intelligence about Irans weapons program in August but did not explain what it was in detail. As recently as October, Mr. Bush continued to warn darkly of Irans nuclear weapons threat, invoking World War III, despite the new information. He responded to a question about that today by saying he had received the final assessment, with its drastically altered findings, only last week. Thats not believable, said Senator Joseph R. Biden Jr. of Delaware, the Democratic chairman of the Senate Foreign Relations Committee and a candidate for president. I refuse to believe that. If thats true, he has the most incompetent staff in American, modern American history and hes one of the most incompetent presidents in modern American history. While many officials, lawmakers and diplomats focused on the halting of Irans weapons program, Mr. Bush emphasized the reports finding that a growing amount of intelligence indicates Iran was engaged in covert uranium conversion and uranium enrichment activity from the late 1980s until the freezing of that effort in 2003. Mr. Bushs senior aides describe that as the first evidence of what many officials had only suspected. And so I view this report as a warning signal that they had the program, Mr. Bush said. They halted the program. And the reason why its a warning signal is that they could restart it. Critics, though, blamed the Bush administrations hard line and harsh language for compounding Irans determination and undermining diplomatic efforts. They called on the administration to make a more concerted diplomatic effort to persuade Irans government to abide by its commitments to the International Atomic Energy Agency. Their actions have been totally self-defeating, Mr. Biden said of the Bush administration. Every time they rattle the saber, what happens is the security premium for oil goes up. It raises the price of oil. It puts more money in the pocket of Ahmadinejad and the very people we think are the bad guys. Mr. Bush maintained that the administration had made offers to Iran as part of the European Unions diplomatic efforts as long ago as 2003, including promising American support for membership in the World Trade Organization and an easing of sanctions to allow the sale of spare airplane parts. What changed was the change of leadership in Iran, he said, referring to the elections in Iran in 2005. We had a diplomatic track going, and Ahmadinejad came along and took a different tone. And the Iranian people must understand that the tone and actions of their government are that which is isolating them. Flynt Leverett, a Middle East expert at the New America Foundation who once served on the National Security Council under Mr. Bush, said the president had consistently ruled out any real entreaty to Iran that could resolve the international deadlock over its nuclear ambitions. The really uncomfortable part for the administration, aside from the embarrassment, is the policy implication, Mr. Leverett said of the new intelligence assessment. The dirty secret is the administration has never put on the table an offer to negotiate with Iran the issues that would really matter: their own security, the legitimacy of the Islamic republic and Irans place in the regional order. Steven R. Weisman contributed reporting.