In what is seen as one of its harshest warnings in decades, Russia has threatened to aim missiles at the U.S.-NATO nuclear shield in Europe. President Dmitry Medvedev accused the United States and NATO allies of ignoring Moscow's concerns about the shields.

Medvedev said in a statement Wednesday that appeared to be aimed more at a domestic audience -- Russia is headed for parliamentary elections on December 4 -- that he still hopes for a deal with the U.S. on missile defense. However, the Kremlin would take military countermeasures if the U.S. continues to build the shield without legal guarantees the shields will not be aimed at Russia, he said.

The Russian president's remarks were not taken lightly, but neither did they appear to throw Washington into a panic.

"I do not think it's worth reiterating that the European missile defense system that we've been working very hard on with our allies, and with Russia over the last few years is not aimed at Russia," responded a Pentagon spokesperson. "It is designed to help deter and defeat the ballistic missile threat to Europe and to our allies from Iran."

Medvedev emphasized that Moscow wants a binding agreement, one that ensures the shield will not be aimed at Russia's nuclear missiles. "When we propose to put it on paper in the form of precise and clear legal obligations, we hear a strong refusal," he said.

White House spokesman Tommy Vietor responded that the U.S. will continue to seek Russia's agreement. However, he said, Moscow must realize that "the missile defense systems planned for deployment in Europe do not and cannot threaten Russia's strategic deterrent."

If an agreement is not reached, Russia says it will station its missiles in Kalingrad, a westernmost region which is bordered on all sides by NATO allies. Medvedev declined to specify whether the missiles would carry nuclear warheads.

NATO secretary-general Anders Fogh Rasmussen told reporters he was "very disappointed" with the Russian president's threat.