On Thursday, the ministry said that the U.S. had made a formal reply to Moscow's proposals that Washington utilize its radars in Azerbaijan and southern Russia to counter possible missile attacks from "rogue regimes." The ministry added that it was studying the reply, and declined to comment further.
The United States plans to deploy interceptor missiles in Poland and a radar in the Czech Republic. Moscow views the plans as a threat to its national security.
A source at the Foreign Ministry said that the reply was not what Moscow had expected, and contradicted earlier U.S. pledges.
"Initial studies show that our hopes have not been justified. This is not what Russia was promised at talks in Moscow [in October] in the '2+2' format [between the foreign and defense ministers]," the source said.