Money that Saddam Hussein withdrew from the Iraqi Central Bank may be funding attacks on coalition forces in Iraq, say US officials.
Troops have found millions of US dollars stashed in Baghdad
Iraq's toppled leader apparently authorised the removal of about $1bn in US dollar notes on three trucks hours before bombs began to fall on Baghdad.
Most of the money has been recovered, but some $132m is still missing, US officials told ABC News.
That money may be being used to bolster the resistance campaign, they said.
Saddam's younger son Qusay - killed by US forces in July - is said to have collected the money in the early hours of 19 March.
According to the ABC News report, he obtained the funds by producing a simple handwritten authorisation from Saddam Hussein, later found by US agents in the bank's files.
They have concluded the note is genuine after consulting captured Iraqi officials, including the former finance minister Hikmat Ibrahim al-Azzawi.
Security guards reportedly loaded the notes - packed in stainless briefcases, each holding $1m to $2m - onto three flatbed trucks.
A day later, on 20 March, the US bombardment of Baghdad began.
Coalition forces in Iraq are facing a campaign of resistance that is increasing in ferocity.
In November the US military lost 79 soldiers mostly in enemy attacks - its worst monthly death toll since President George Bush declared the end of major combat.
"We think some of those funds could be used to fuel those attacks and lends greater urgency to our efforts," Juan Zarate, deputy assistant secretary of the US Treasury, told ABC News.
He is at the forefront of the government's effort to track down Saddam's money.
The US Government is also trying to trace how the notes found their way from Federal Reserve Banks in Washington and New York to Baghdad despite tough sanctions on Iraq.
According to US officials, Mr al-Azzawi said a British-based bank in London was unknowingly used as a go-between for funds sent from the US to Beirut and Amman.
"This regime was out to game the system for its own purposes," said Mr Zarate.
"To pay for pleasure palaces, to pay for arms, to pay for weapons."