WASHINGTON - Iran halted its nuclear weapons program four years ago and seems less determined to revive it but is still enriching uranium, U.S. intelligence agencies said Monday in an abrupt about-face on previous views of the country's atomic goals.

While the White House has been escalating warnings about Iran's intentions in recent weeks, intelligence officials have been sorting through new information that suggests Iran does respond to diplomatic and financial pressure.

President George W. Bush even referred to World War III and a "nuclear holocaust'' this fall when talking about Iran's intentions, sparking fears in Congress that he was building up to an invasion.

It turns out Iran stopped its covert program in the fall of 2003 under international pressure and didn't resume at least through mid-2007, according to the latest U.S. intelligence estimate from all 16 American spy agencies.

Still, the country continues to enrich uranium for its civilian energy program, meaning it could develop a weapon between 2010 and 2015.

"Tehran's decision to halt its nuclear weapons program suggests it is less determined to develop nuclear weapons than we have been judging since 2005,'' said the report.

"But we do not know whether it currently intends to develop nuclear weapons,'' it said.

The document was described as an "extensive re-examination'' of its previous May 2005 assessment which said there was "high confidence'' Tehran was determined to develop them.

Bush was briefed on the 100-page report last Wednesday.

Stephen Hadley, the White House national security adviser, told a briefing that the U.S. spy agencies weren't wrong about Iran having a covert program at one time.

"I would say to you they got it right in terms of being concerned about Iran seeking a nuclear weapon and we continue to be concerned about a nuclear weapon.''

The report is no excuse to think "the problem's less bad than we thought,'' he said.

"Our view is that would be a mistake because Iran is still trying to enrich uranium,'' a critical component of weapons-grade nuclear material' said Hadley.

But the estimate does offer grounds for hope the problem can be solved diplomatically without the use of force, he said, adding that Bush has had the right strategy.

"The bottom line is that for that strategy to succeed, the international community has to turn up the pressure on Iran with diplomatic isolation, United Nations sanctions and with other financial pressure and Iran has to decide that it wants to negotiate a solution,'' said Hadley.

Tensions with Iran have been increasing since Mahmoud Ahmadinejad became leader in 2003.

Iran denies that it is using a civilian atomic energy program to develop nuclear weapons. But Bush has said the United States will only join negotiations with Tehran after it suspends uranium enrichment, something Ahmadinejad has rejected.

The United States recently slapped sanctions the Mideast country and is pushing hard for more from the UN.

Officials say Iran is the most difficult country to spy on because it is such a closed society.

Bush reorganized the intelligence agencies after they produced faulty evidence that former Iraqi dictator Saddam Hussein had weapons of mass destruction.

The president used the intelligence as a basis for invading Iraq.