The Pentagon, however, has said a US military buildup in the Gulf represents a message to "potential adversaries" in the region, and Bush has vowed to crush any Iranian networks fuelling violence claiming the lives of US soldiers in Iraq.

"I guess my reaction to all the noise about, you know, 'he wants to go to war,' is -- first of all I don't understand the tactics, and I guess I would say it's political," Bush told CSPAN television in an interview.

"On the other hand, I hope that the members of Congress, particularly in the opposition party, understand the great danger of Iran having a nuclear weapon," the US president said.

Referring to the nuclear dispute, Bush said he had "a comprehensive policy aimed to solve this peacefully" and vowed to "press hard" for Iran to freeze sensitive nuclear work that could be a key step towards an atomic arsenal.

Tehran has rejected charges of smuggling bombs to insurgents who target US troops as "without foundation" and has repeatedly denied Washington's allegations that its nuclear program hides a quest for an atomic bomb.

The White House, its credibility badly damaged by the flawed case for invading Iraq, vouched for charges that Iranians had been arming insurgents in Iraq with deadly bombs with the knowledge of the government in Tehran, while denying that this spells likely military action.

"I don't think there's a change of tone on our part," said spokesman Tony Snow. "I think that there have been attempts, with all due respect, in the press to try to whip this up -- 'is the administration going after Iran?'"

"I'm glad you raised it again, because we're not," said Snow.

Asked to give proof that Tehran knew about the bomb shipments, the spokesman replied: "Let me put it this way: There's not a whole lot of freelancing in the Iranian government, especially when it comes to something like that."

"To counter that position, you would have to assume that people were able of putting together sophisticated weaponry, moving it across a border into a theater of war and doing so unbeknownst and unbidden," he said.

Snow declined to offer more details, referring reporters to the Pentagon, and when asked whether the US military had provided him details of the case against Iran he replied: "I didn't get briefed on it."

His comments came one day after top US defense officials said in Baghdad that sophisticated Iranian-built bombs smuggled into Iraq have killed at least 170 US and allied soldiers since June 2004 and wounded 620 more.

Three coalition officials met international and Iraqi journalists to point the finger at the Al-Qods brigade of the Iranian Revolutionary Guard, Tehran's elite forces.

They spoke on condition of anonymity and cameras and recording devices were barred from the briefing, at which an array of mortar shells and booby traps were laid out for inspection.

Opposition Democrats and even some of Bush's Republicans have criticized the administration for its tough talk on Iran, warning that they hear echoes of the flawed case for the March 2003 US-led invasion of Iraq.

"I look at this with a degree of skepticism, based on the record that these intelligence operations have provided us in the past," said Christopher Dodd, a member of the Senate Foreign Relations Committee, who has expressed an interest in running for president in 2008.

Dodd told CBS television Sunday he had no doubt that Iran played a role in the current unrest in Iraq, but believed the issue should be resolved through diplomacy.

"It seems to me until we engage them in some way on a multiple of issues, including this one, it's only going to get worse," the Connecticut senator said.

Senator and former Democratic presidential nominee John Kerry said the administration's charges of Iranian meddling will be met by "a skeptical Congress, and appropriately so, because of the last experience with Iraq."

Bush's administration, still smarting from the now-discredited charges that Saddam Hussein's Iraq possessed weapons of mass destruction, has struggled with how to back up its allegations against Iran.

After promising for weeks to reveal evidence underpinning its allegations that Tehran had been arming Iraqi insurgents, the White House scrapped a briefing almost at the last minute.

"The truth is, quite frankly, we thought the briefing overstated. And we sent it back to get it narrowed and focused on the facts," Bush national security adviser Stephen Hadley said February 2.

All rights reserved. � 2005 Agence France-Presse. Sections of the information displayed on this page (dispatches, photographs, logos) are protected by intellectual property rights owned by Agence France-Presse. As a consequence, you may not copy, reproduce, modify, transmit, publish, display or in any way commercially exploit any of the content of this section without the prior written consent of Agence France-Presse.