Updated

MOSCOW -- A deal with Washington to assuage Moscow's concerns about U.S. missile defense plans in Europe is still possible, but time is running out, Russia's foreign minister said Wednesday.

Sergey Lavrov reaffirmed that Moscow will take retaliatory action if moves by Washington to deploy missile shield components around Europe pose a threat to Russia.

The U.S. says its planned missile shield is aimed at deflecting potential missile threats from Iran, but Russia fears that the missile shield will eventually grow powerful enough to undermine Russia's nuclear deterrent.

"Like any responsible state, we proceed not from declarations, but from concrete action when it comes to security issues," Lavrov said. "Our response will strictly correspond to the potential of the European component of the U.S. missile defense as it develops."

Moscow agreed in 2010 to consider NATO's proposal to cooperate on the U.S.-led missile shield, but the talks have run into a deadlock over how the system should be operated. Russia has insisted that it should be run jointly, which NATO has rejected.

In a televised address to the nation in November, President Dmitry Medvedev threatened to deploy missiles to the Kaliningrad region, bordering Poland and Lithuania, and to other areas of Russia to be aimed at U.S. missile defense sites, if the U.S. and NATO fail to reach a deal allaying Russian worries. He urged the U.S. to provide firm and specific guarantees that its future missile defense potential will not be directed against Russia.

Lavrov said Wednesday that Russia doesn't want confrontation with the U.S. and doesn't think that Washington is making a specific effort to erode Russia's nuclear deterrent.

But he added that the growing power of the U.S. missile shield could eventually make it capable of engaging Russia's nuclear forces. "I hope that it's not their goal, but its development undermines the strategic parity," he said.

"We still have time to solve the acute problems, but it's not unlimited," Lavrov said, adding that Russia hopes that differences over missile defense wouldn't throw Moscow and Washington back to a Cold War-style pattern of confrontation. "We must be heard and there must be a response to our legitimate concerns."

Washington's missile defense plans have been a key irritant in U.S.-Russian relations since President Ronald Reagan's "Star Wars" plans that spooked the Kremlin in the 1980s.

The current toughening of Moscow's rhetoric has posed a challenge to President Barack Obama's policy of "resetting" relations with the Kremlin, which suffered badly under George W. Bush's administration.