WASHINGTON -- A Russian military transport plane that delivered cargo to a U.S. base in Alabama earlier this week was carrying Soviet antiaircraft and antimissile equipment, according to Pentagon officials.


The precise contents of the plane are still classified. But Pentagon officials, speaking Wednesday on condition of anonymity, said the plane carried air defense technology developed by the former Soviet Union.


"None of it is nuclear and none of it is lethal," said one defense official.


The United States purchased the equipment under contract as part of a continuing effort to study in detail the capabilities of weapons systems used by foreign governments. The identity of the seller is also classified but it was probably one of the former Soviet republics.


The air defense system delivered Monday to the Redstone Arsenal, a U.S. Army base in Huntsville, Alabama, was sold by the Soviets to foreign countries and is still in use in several of them.


"We routinely acquire foreign equipment for evaluation," another defense official said. "We study and analyze that equipment, determine capabilities and limitations, and then use that information to our benefit."


The delivery attracted attention because a Russian An-124, one of the world's largest planes, made the delivery.


Redstone has received secret military cargo many times in the past, but it always arrived aboard airplanes that could land at the army base, said Dave Harris, a civilian public information officer at the base. The An-124, however, was too large for the runway and had to land at Huntsville's International Airport and the cargo was trucked to the base.