"Our missiles planned for basing in Europe will not be aimed at Russia and have no capability against Russian missiles," McFaul said on his Twitter account.
Russian President Dmitry Medvedev said Friday the United States was running out of time to secure Russia's support for a missile defense shield in Europe. He added NATO is unconvinced the shield was intended to protect against attack from countries such as Iran.
"We have time [for an agreement] but it is running out, and I think that it would be in our mutual benefit to reach mutually acceptable agreements," he said at a security conference.
Despite the disagreement, NATO and Russia have been working together in the war in Afghanistan, as well as a number of anti-drug and anti-piracy operations, the Russian news agency RIA Novosti reported.