Unrest in Iraq is providing Islamist militants with training and contacts that could be used in new attacks abroad, the head of the CIA has warned.
Goss says insurgents could go on to build transnational cells
In his first public appearance as CIA director, Porter Goss said the conflict had become a "cause for extremists".
It was only a matter of time, he added, before militant groups like the al-Qaeda network attempted to use weapons of mass destruction.
Mr Goss was testifying before a Senate hearing on threats to the US.
More than three years after the 11 September 2001 attacks, the CIA director stressed that militants were still trying to strike inside the US.
The Bush administration cited links between Saddam Hussein and the 11 September hijackers as a main reason for invading Iraq.
The US later said it had found no evidence of contacts between Iraq and the hijackers.
Mr Goss said the ongoing Iraq conflict, "while not a cause of extremisms, has become a cause for extremists".
One US terrorism expert said Mr Goss's remarks indicated he was not taking marching orders from the White House.
"Goss is very much listening to what his analysts are saying, and not necessarily to what the White House wants to hear," Kenneth Katzman of the Congressional Research Service told the Reuters news agency.
Mr Goss also accused Iran of supporting terrorism, aiding Iraqi insurgents and seeking to acquire nuclear weapons.
FBI director Robert Mueller, who also testified, warned: "The threat posed by international terrorism, and in particular al-Qaeda and related groups, continues to be the gravest we face."
Mr Goss, one of several intelligence chiefs to appear before the panel, was providing the CIA's annual threat assessment.
Correspondents say the committee has decided to subject US foreign intelligence to new scrutiny in the hope of avoiding mistakes committed before the war on Iraq.
Mr Goss' predecessor, George Tenet, resigned amid criticism of flawed intelligence used before the 2003 invasion of Iraq.
The new CIA head said threats to the US both at home and abroad remained, despite successes against al-Qaeda, but the network was now only one facet of a wider threat.
In Iraq, he said, the militant Abu Musab al-Zarqawi was seeking to exploit the conflict to recruit for broader operations.
"Those jihadists who survive will leave Iraq experienced in and focused on acts of urban terrorism," he said.
"They represent a potential pool of contacts to build transnational terrorist cells, groups and networks."
He added that despite successful elections in Iraq on 30 January, a spate of bomb attacks in recent weeks and the unwillingness of Sunni Arabs to vote showed that the insurgency remained a threat to stable representative government.