From GWB's speech on Monday at GWU:
Some of the most powerful IEDs we are seeing in Iraq today includes components that came from Iran. Our director of National Intelligence, John Negroponte, told the Congress Tehran has been responsible for at least some of the increasing lethality of anti- coalition attacks by providing Shi'a militia with the capabilities to build improvised explosive devices in Iraq. Coalition forces have seized IEDs and components that were clearly produced in Iran.
President George W. Bush said on Monday components from Iran were being used in powerful roadside bombs used in Iraq, and Defense Secretary Donald Rumsfeld said last week that Iranian Revolutionary Guard personnel had been inside Iraq.
Asked whether the United States has proof that Iran's government was behind these developments, Marine Corps Gen. Peter Pace, chairman of the military's Joint Chiefs of Staff, told a Pentagon briefing, "I do not, sir."