U.S. troops in Afghanistan have destroyed the largest cache of weapons yet found in the country. But, the weapons that were found and destroyed were somewhat unusual.

Since launching operations in Afghanistan one year ago, U.S. forces have uncovered scores of weapons caches. Usually, the finds have featured rocket-propelled grenades, mortars, machine guns, small arms and ammunition.

This time, troops discovered and destroyed some 420 aerial bombs, each weighing more than 200 kilograms.

Chief Defense spokeswoman Victoria Clarke said Friday there was a lesson to be learned from the find - that there was still more military work to be done in the country. She also cited the find near Kandahar as evidence that the al-Qaida and the Taleban remain intent on harm. "It is an example of how much work we have yet to do," she said. "We continue to find caches of weapons and ammunition. Clearly, the al-Qaida, the Taleban had a great deal of intent, some still have intent, to do harm."

There was just one problem with the announcement, though. Defense officials later conceded there was no evidence to link either the Taleban or the al-Qaida to the bombs.

Instead, officials said the explosives found near Kandahar were in fact Soviet-era weapons, stockpiled and then apparently abandoned during the Soviet occupation of Afghanistan in the 1980's.

Explosives experts described the aged bombs as too dangerous to move and blew them up where they had been found buried underground.

Still, some U.S. officials voiced concern that Taleban or al-Qaida fighters, had they found them, could have used the bombs as terrorist weapons, perhaps in a car bomb.

There have been several terrorist bombings over the past year, especially in the Afghan capital, Kabul.