"I view this report as a warning signal that they had the program, they halted the program," Mr. Bush said. "The reason why it's a warning signal is they could restart it."
Mr. Bush spoke one day after a new national intelligence estimate found that Iran halted its nuclear weapons program in the fall of 2003, largely because of international scrutiny and pressure. That finding is in stark contrast to the comparable intelligence estimate of just two years ago, when U.S. intelligence agencies believed Tehran was determined to develop a nuclear weapons capability and was continuing its weapons development program.
It is also stood in marked contrast to Mr. Bush's rhetoric on Iran. At his last news conference on Oct. 17, for instance, he said that people "interested in avoiding World War III" should be working to prevent Iran from having the knowledge needed to make a nuclear weapon.
In question after question, reporters wanted to know if the American people should feel misled by his years of assertions that Iran was pursuing nuclear weapons, reports CBS News White House correspondent Mark Knoller.
One reporter asked if Mr. Bush could be accused of hyping the Iranian threat. Another even apologized in advance for suggesting that Mr. Bush's body-language made him look dispirited.
"All of a sudden, it's like Psychology 101," responded the president, dismissing the reporter's suggestion.
CBS News chief White House correspondent Jim Axelrod asked the president if at any point while his rhetoric against Iran was escalating in October, anyone from his intelligence team or administration had cautioned him to temper his language.
"No," Mr. Bush answered him. "Nobody ever told me that. Having said - having laid that out, I still feel strongly that Iran is a danger."
He clearly felt no apology was warranted for years of public warnings of Iran's pursuit of nuclear weapons.
Mr. Bush said that he only learned of the new intelligence assessment last week. But he portrayed it as valuable ammunition against Tehran, not as a reason to lessen diplomatic pressure.
"To me, the NIE (National Intelligence Estimate) provides an opportunity for us to rally the international community - to continue to rally the community - to pressure the Iranian regime to suspend its program," the president said. "What's to say they couldn't start another covert nuclear weapons program."
Jon Alterman,the director of the Middle East program at the Center for Strategic and International Studies, told CBS News that the effect of the intelligence report may have just the opposite effect on the international community.
"The momentum is going to move away from the world coming together," Alterman said, "because that sense of urgency that had dominated this issue has just gone away."
President Bush also asserted that the report means "nothing's changed," focusing on the previous existence of a weapons program and not addressing the discrepancy between his rhetoric and the disclosure that the weapons program has been frozen for four years.
"I still feel strongly that Iran is a danger," he said. "I think the NIE makes it clear that Iran needs to be taken seriously as a threat to peace. My opinion hasn't changed."
Mr. Bush said the report's finding would not prompt him to take a U.S. military option against Tehran off the table.
"The best diplomacy - effective diplomacy - is one in which all options are on the table," he said.
Mr. Bush called the news conference, his first in nearly seven weeks, to intensify pressure on lawmakers amid disputes over spending and the Iraq war. Taking advantage of his veto power and the largest bully pulpit in town, Mr. Bush regularly scolds Congress as a way to stay relevant and frame the debate as his presidency winds down.
Democrats counter that Mr. Bush is more interested in making statements than genuinely trying to negotiate some common ground with them.
Specifically, Mr. Bush again on Tuesday challenged Congress to send him overdue spending bills; to approve his latest war funding bill without conditions; to pass a temporary to fix to the alternative minimum tax so millions of taxpayers don't get hit with tax increases; and to extend the Foreign Intelligence Surveillance Act.
"Congress still has a lot to do," Mr. Bush said. "It doesn't have very much time to do it."