SOCHI -- President Dmitry Medvedev said Russia would respond militarily to the deployment of U.S. missiles close to its borders under a plan for a missile shield.

"These missiles are close to our borders and constitute a threat to us," Medvedev told Al-Jazeera television late Tuesday. "This will create additional tension and we will have to respond to it in some way, naturally using military means."

Medvedev had spoken before of a possible military response, but Tuesday's remarks were the first on these lines since U.S. Secretary of State Condoleezza Rice signed an agreement in Poland last week on deployment of 10 U.S. interceptor rockets there.

Washington says the shield, also involving a radar station in the Czech Republic, is intended to protect against launches by "rogue states" like Iran.

Russia rejects U.S. arguments for the shield and presents it as a move threatening its nuclear defenses.

Russian military and political leaders have never specified what military steps they might take.