Anatoly Antonov, Russia's lead negotiator with NATO on the planned Western European missile-defense system, said the discussions have reached "a dead end."
In an interview with "Kommersant" newspaper, Antonov, who is deputy defense minister, criticized Western proposals on missile defense as "vague," adding that Russian participation in a European missile-defense system "is not even up for discussion."
He named the proposed U.S.-led missile-defense system in Europe as the main threat to Russian security and said Moscow might withdraw from the new START, the Strategic Arms Reduction Treaty signed with Washington in 2010.
Antonov was repeating positions stated by Foreign Minister Sergei Lavrov on February 4.
Lavrov criticized Washington for failing to provide assurances that the proposed system is not directed against Russia's nuclear deterrent.
NATO allies agreed in November 2010 to develop a missile-defense shield that would protect member states against long-range attacks from states such as Iran.