(CNN) -- Poland and the United States will sign a preliminary deal to place part of a U.S. ballistic missile defense system in Poland -- a plan that has drawn sharp objections from Russia, the Polish president's office confirmed Thursday to CNN.

The Bush administration has long pushed to base missile interceptors in Poland. The interceptor rockets would be linked to an air-defense radar system in the Czech Republic, whose officials agreed in April to take part in the system.

Both countries are former Soviet satellites but now are members of the U.S.-led NATO alliance. The United States' plans to base the anti-missile system in Eastern Europe have raised alarms in Russia.

Moscow has mounted serious opposition to the missile shield plan, although the United States has insisted it is designed to counter threats from the Middle East and is not an aggressive move against Russia.

The United States has also agreed to help Poland modernize its military, which it requested as a condition of its support for housing the missile defense system.

Thursday's agreement comes amid heightened tensions between the United States and Russia over Moscow's invasion of Georgia, a U.S. ally