The United States has dismissed a Russian offer to abandon a plan for deploying missiles if the U.S. European defense shield is dropped, officials said.

But a State Department spokesman said diplomatic officials are interested in talks with Moscow to ease Russian concern about the U.S. missile defense system in Europe, Voice of America reported Friday.

Spokesman Robert Wood said efforts are still under way to arrange a Moscow visit by the department's arms control chief to discuss the proposals.

"We believe it's in the best interests of the United States and its European allies. We think it's something Russia needs to take seriously, these future threats from the Middle East," Wood said. "We want to cooperate with Russia, but we need a partner."

Russian President Dmitry Medvedev threatened to respond to the defense plan by deploying short-range Iskander missiles in Russia's Kaliningrad enclave bordering Poland, where U.S. interceptor missiles would be based. He later said he'd abandon the deployment if the U.S. scrapped its defense plan.

Russia opposes the defense system as a threat to its national security. The United States says the shield is needed to protect Europe against attacks from rogue states.

U.S. Defense Secretary Robert Gates said Moscow's offer wasn't credible, explaining that the "only real emerging threat" to Russia is Iran and that he didn't believe the Iskander missiles would reach the Mideast country from Kaliningrad.