The US Army awarded $192,000 (£122,000) in contracts in 2002 to a Russian company identified in news reports as a supplier of Global Positioning System (GPS) jamming equipment to Iraq.
The reports said Moscow-based Aviaconversiya has denied selling the jamming equipment to Iraq.
On Tuesday, President Bush personally complained to Russian Premier Vladimir Putin about the sale of Russian military equipment to Iraq, according to White House spokesman Ari Fleischer.
In a press briefing that day, Fleischer said the White House was "concerned" about reports "of ongoing co-operation and support to Iraqi military forces being provided by a Russian company that produces GPS jamming equipment ... We have credible evidence that Russian companies provided the assistance and the prohibited hardware to the Iraqi regime.
"The President raised with President Putin our ongoing concerns about support [that] would be provided for Iraqi military forces by Russian companies that produced the equipment."
Fleischer said Putin had promised to look into the issue.
Iraq evidently tried to use those jammers against US forces after the US-led coalition began strikes against Iraqi targets last week. "We have noticed some attempts by the Iraqis to use a GPS jamming system that they obtained from another nation. We have destroyed all six of those jammers in the last two nights' airstrikes. I'm pleased to say they had no effect on us," Air Force Major General Victor Renuart of the US Central Command, said on Wednesday.
USAF Lieutenant Colonel Ken McClellan, a US Defense Department spokesman, acknowledged that the Army had awarded contracts to Aviaconversiya. The company is included on an online list of all Defense Department contracts worth more than $25,000 that were awarded in 2002. But he declined to provide any details.
GPS experts said the Army most likely bought equipment from Aviaconversiya to test its capabilities which, in turn, would help US forces avoid jamming or attack jammers being used against them.
But GPS consultant James Hasik said he doubted that the jammers would have much effect on GPS-equipped smart weapons used in Iraq, such as the Tomahawk cruise missile or Joint Direct Attack Munitions, because they have backup guidance systems such as gyroscope-based inertial navigation systems.
Hasik said jamming of civil signals could be detrimental if pilots of ageing aircraft like the Air Force A-10 or the Navy F-14 have bought handheld commercial receivers to make up for those planes' lack of built-in GPS. Jamming could interfere with critical navigation functions of the receivers.
GPS receivers are susceptible to jamming because of the weak nature of the signals as they travel to receivers on earth from 24 satellites in space, Hasik added.
This week's warning about the sale of Russian GPS jammers to Iraq and the subsequent attack on them illustrate the Pentagon's concern about interference with one of the core technologies of its smart weapons systems.
Earlier this year, McClellan said the Pentagon had a "somewhat serious concern" about an online article in hacker magazine Phrack that detailed how to build a homemade GPS jammer.