Eric Edelman, undersecretary of defense for policy, said the United States wanted to cooperate with Russia and that he was still "very hopeful" the two would reach an understanding.
But he said if talks failed, the United States would not allow Russia to "dictate what we do bilaterally with other countries."
Russia has strongly objected to the plan to put a radar system in the Czech Republic and missile interceptors in Poland.
But the United States says the shield would pose no threat to Russia and that it is meant to guard against what it says are potential attacks from "rogue states" such as Iran.
The Proliferation Threat
The Arak heavy-water plant in central Iran (Fars)
BENDING THE RULES. Henry Sokolski, executive director of the Nonproliferation Policy Education Center, told an RFE/RL-Radio Free Asia briefing on January 9 that the West is hamstrung in dealing with Iran and North Korea because of the way it has interpreted the international nonproliferation regime to benefit friendly countries like India and Japan.
LISTENListen to the entire briefing (about 90 minutes):
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