Russia can not allow U.S. plans to deploy elements of its missile shield in Europe to threaten the effectiveness of its nuclear deterrent, Russian Foreign Minister Sergei Lavrov said on Wednesday.

U.S. officials admit that the missile defense system in Europe might be able to hit Russian inter-continental ballistic missiles by 2020.

"The U.S. administration says its global missile shield program is not directed against Russia. However, our conclusions on the true potential of the future missile defense system should be based on specific military and technical factors, not on words," Lavrov said.

"We will not accept a state of affairs when a missile defense system poses a threat to Russia's nuclear deterrence potential," he went on.

Bulgaria and Romania have said they are in talks with the United States on hosting elements of its missile shield on their soil. The planned deployment of U.S. interceptor missiles into the Black Sea region triggered fierce criticism from Moscow.

The planned deployments in Bulgaria and Romania come after President Barack Obama scrapped earlier plans for a radar and interceptor missiles in the Czech Republic and Poland, which Russia vehemently opposed as a national security threat and a blow to its nuclear deterrent.

Russian Defense Minister Anatoly Serdyukov warned last month that Russia could still deploy Iskander missiles in its exclave on the Baltic Sea if new threats emerge in Europe.

Lavrov said it was too early to talk about Russia's response to the U.S. missile shield plans as Washington is still to make a final decision on the scheme.

MOSCOW, March 10 (RIA Novosti)