Russian President Dmitry Medvedev lashed out Wednesday at the United States over its plans for a missile shield in Europe, saying a U.S. deal to install part of the system in Czech Republic "deeply distresses" Moscow.

He vowed a response to the planned U.S. system but stopped short of specifying what kind.

A day earlier, the Russian Foreign Ministry threatened a military response if the agreement U.S. Secretary of State Condoleezza Rice signed in the Czech Republic is ratified.

Medvedev echoed his predecessor Vladimir Putin's bitter tone on a topic at the center of strained ties with Washington. He suggested the U.S., instead of honestly addressing Russia's concerns, has been stringing it along with "halfhearted negotiations that have come to nothing."

The United States wants to place tracking radar in the Czech Republic and missile interceptors in Poland _ two NATO nations formerly in the Soviet-controlled Warsaw Pact.

"The situation deeply distresses us," Medvedev said.

"We of course will not raise hysteria over this, but we will think of further steps in response to it," he said.

Russia says it is not convinced by U.S. insistence that the shield is meant to neutralize a potential Iranian threat and suspects the true aim is to weaken Russia's nuclear deterrent, altering the balance of power between the Cold War foes.

"We have repeatedly underscored _ both earlier and during this summit I spoke of this _ that questions of European security must be resolved in a different way," Medvedev told a news conference after a summit of the Group of Eight leading industrialized nations in Japan. Continued...