Pentagon spokeswoman April Cunningham confirmed in a Kommersant newspaper article published Monday that Bradley Roberts, U.S. deputy assistant defense secretary, said "secret data" on the shield would be shared with Russia, RIA Novosti reported.
The Russian news agency said it remained unclear what information would be shared about the missile-defense system, which would be deployed in Eastern Europe and include Poland, Romania and the Czech republic.
The United States has said the system is designed to protect against a potential threat from countries such as Iran and North Korea.
Russia and NATO have agreed to cooperate on a European missile shield, but Russia has said it was concerned the NATO missile-defense system would allow the West to attack Russia without the risk of a retaliatory strike.
Officials in Russia have said they were concerned a NATO missile-defense system would allow the West to attack Russia without the risk of a retaliatory strike.
Alexander Khramchikhin, a researcher with the Moscow-based Institute for Political and Military Analysis think tank, said the Russian military needs to know only the speed of missile-defense system interceptor rockets to determine whether the shield would present a risk to Russian rockets.