WASHINGTON - President Bush scrambled yesterday to hold together a fragile international coalition against Iran, declaring that the Islamic republic remains "dangerous" and that "nothing has changed" despite the new intelligence report that Iran halted its nuclear-weapons program in 2003.

While his top diplomats reached out to key counterparts, Bush began calling world leaders and held a news conference to argue that the new National Intelligence Estimate only reinforced the need for diplomatic pressure against Iran. Bush said Tehran's secrecy showed it could not be trusted.

The new intelligence electrified Washington and foreign capitals, transforming the debate on what has been widely characterized as a central threat to international security. It dominated a Democratic presidential debate yesterday. And it once again put the credibility of the U.S. government in dispute five years after intelligence agencies wrongly reported that Iraq had weapons of mass destruction.

Iranian leaders boasted that the new report vindicated them, but European allies agreed with Bush that Tehran's continued uranium-enrichment program for what it says are civilian purposes remained a threat meriting international action.

A senior U.S. envoy won agreement from other permanent U.N. Security Council members and Germany to push for additional sanctions, according to U.S. and foreign officials, though some worried that the consensus would tatter.

Bush defended his approach, saying "our policy remains the same" regardless of the new intelligence.

"Look, Iran was dangerous, Iran is dangerous, and Iran will be dangerous if they have the knowledge necessary to make a nuclear weapon," he said. "The NIE says that Iran had a . . . covert nuclear-weapons program. That's what it said. What's to say they couldn't start another covert nuclear-weapons program?"

The estimate, based on intercepted communications and other fresh information gathered in recent months, concluded that Iranian leaders tried to develop nuclear weapons until 2003, when diplomatic pressure led them to halt the effort. The finding was a striking about-face from a 2005 intelligence report that said Iran was actively trying to build a bomb, and it undercut stark warnings by Bush in recent years.

Bush said the willingness to reverse the assessment showed the success of his effort after the Iraq debacle to revamp U.S. intelligence and make it more open to contrary information.

He said he was first told about the new information in August by Mike McConnell, the director of national intelligence, but not in detail: "In August, I think it was Mike McConnell came in and said, we have some new information. He didn't tell me what the information was; he did tell me it was going to take a while to analyze."

Bush made clear it did not change his view and would not have changed his rhetoric, including his October warning about the possibility of World War III if Iran builds nuclear weapons.

He argued that uranium-enrichment technology could be used to help develop weapons and noted that Iran had tested ballistic missiles.

"Nothing has changed in this NIE that says, 'OK, why don't we just stop worrying about it?' " he said. "Quite the contrary. I think the NIE makes it clear that Iran needs to be taken seriously."

While arguing for diplomacy, he repeated that "all options are on the table," including military force.

Bush's comments triggered harsh criticism. Presidential candidate Joseph R. Biden Jr. (D., Del.), chairman of the Senate Foreign Relations Committee, scoffed at the notion that McConnell did not tell Bush the details of the new intelligence in August.

"If that's true," Biden said, "he has the most incompetent staff in modern American history, and he would be one of the most incompetent presidents in modern American history."

In Tehran, Foreign Minister Manouchehr Mottaki welcomed the U.S. assessment and said it was time for other countries to "correct their views." Other Iranian politicians called for a formal apology and compensation for sanctions.

Israel dismissed the importance of the intelligence and called on Washington to keep up the pressure.

The development frustrated U.S. allies. Key diplomats were especially annoyed that the report was released just two days after a U.S.-orchestrated meeting in Paris to discuss the next stage of sanctions.

Bush and his advisers say they are optimistic they can salvage their diplomatic initiative.

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