The Pentagon has again stepped into a row over 350 metric tons of high explosives that went missing in Iraq around the time of the US-led invasion.
Explosives lost at al-Qaqaa have become an issue in the US election
The US defence department revealed that soldiers had removed munitions from the al-Qaqaa military site in April 2003.
However, it could not confirm that this was the same material that the UN's nuclear watchdog has reported missing.
Earlier, a television station released footage apparently showing US troops examining explosives at the site.
The issue of the missing explosives has become a major theme in the US presidential election campaign as voters prepare to go to the polls on Tuesday.
The BBC's Pentagon correspondent, Nick Childs, says that although some analysts have raised questions about the military significance of the cache, it has turned into a political emblem for both sides in this election.
It is providing particular ammunition for the Kerry campaign, he says.
Democratic challenger John Kerry has accused President George W Bush of incompetence for not ensuring that US forces secured the material.
Mr Bush, for his part, has hit back at what he called "wild charges" made by Mr Kerry for political reasons.
The row broke out after the UN's nuclear watchdog, the International Atomic Energy Agency (IAEA), raised concerns over high explosives missing from al-Qaqaa, near Baghdad.
The IAEA said the material, sealed and monitored by its inspectors until the US-led invasion, had gone missing some time after 9 April 2003.
As the controversy continues to swirl, our correspondent says, the Pentagon's approach seems to be to raise questions about some of the assumptions being made as it tries to work out what happened itself.
In a news conference on Friday at the Pentagon, Maj Austin Pearson said his team removed 250 tons of material including TNT and plastic explosives on 13 April 2003.
However, neither he nor Pentagon spokesman Larry DiRita could confirm that the material was part of the weapons cache sealed by the IAEA.
Maj Pearson told reporters: "I did not see any IAEA seals at locations we were looking into."
The Pentagon news conference followed the release of footage shot by a crew embedded with the 101st Airborne Division, which shows troops inspecting explosives at al-Qaqaa on 18 April 2003.
ABC News said experts who had studied the video believed barrels seen in the video contained the high explosive HMX, with UN markings on the sealed containers.
David Albright, a former UN weapons inspector, told ABC the footage appeared to tally with what colleagues had seen at the site and that an IAEA seal was visible.
The IAEA last inspected the munitions at al-Qaqaa in January 2003 but has not been allowed back into Iraq since the invasion.
Analysts say the theft raises the possibility that some explosives could have found their way into improvised devices used against US-led forces in Iraq.
The lost explosives consist mainly of 195 tons of HMX (high melting explosives) and 141 tons of RDX (cyclonite) - both key components in plastic explosives.
On Thursday, US Defense Secretary Donald Rumsfeld said the material was probably taken before the US arrived.
He released an image showing trucks at the site just before the war - but officials admitted it was not clear whether the two trucks had anything to do with the missing explosives.
The declassified image released by Mr Rumsfeld on Thursday appears to show some Iraqi activity at al-Qaqaa on 17 March, days before the invasion.
Mr Rumsfeld said in an interview with US station WABC Radio that it was "very likely" Saddam Hussein had moved the munitions to protect them from attack.