MOSCOW, July 8 (Xinhua) -- Moscow would be forced to respond to U.S. plans to place a missile defense radar in the Czech Republic, the Russian Foreign Ministry said Tuesday after the signing of a U.S.-Czech agreement.

　　"Given this situation, the Russian side will obviously have to take appropriate measures to compensate for the growing potential of threats to its national security. But this is not our choice," the ministry said in a statement.

　　"The measures to provide transparency and control were rejected by the American party," it said. "So, a corresponding agreement between the Russian and U.S. presidents consolidated in a declaration in Sochi on April 6, 2008, is undermined."

　　The statement said Moscow would be still open to constructive talks on the U.S. missile defense plans, but only on equal terms and "based on the need to maintain the required security of our country."

　　U.S. Secretary of State Condoleezza Rice and her Czech counterpart Karel Schwarzenberg signed Tuesday the main treaty on the stationing of a U.S. radar base on Czech soil despite protests from both the Czech public and Russia. The main treaty still needs to be approved by Czech parliament.

　　As part of the missile defense system, the United States plans to place interceptor missiles in Poland, but talks with Warsaw have stalled.

　　Russia has offered the United States the use of its radar stations in Armavir in southern Russia and Gabala in Azerbaijan as alternatives, but Washington said they could only be used as supplements.