WARSAW, Poland — The United States will deploy anti-missile interceptors, upgrade Poland's air defenses and modernize its military under two agreements signed Wednesday.

The agreements, signed by Secretary of State Condoleezza Rice and Polish Prime Minister Donald Tusk, are almost certain to increase the already high tensions between Russia and the West over the Russian invasion of Georgia.

Russia already has threatened to target Poland — perhaps even with nuclear weapons — for agreeing to host the launch site for 10 anti-missile interceptors that would be part of the American missile-defense system.

The Bush administration also is planning to place a sophisticated tracking radar in the Czech Republic.

It says that the units are designed to shoot down warheads from Iran, which is developing long-range missiles.

Moscow, however, charges that the facilities will be used to neutralize its strategic nuclear missiles.

"Missile defense is aimed at no one," Rice said during Wednesday's signing ceremony.

Under the pacts, the United States also will improve Poland's air defenses, including deploying a Patriot air-defense battery operated by American troops.

The United States also will help modernize Poland's military, which already receives more American military aid than any other European nation.

At a news conference later, Rice rejected the notion that the new arrangement would anger Moscow.

"I hope that there are not people in Russia who are hankering for the days of U.S.-Soviet confrontation, because they are over," she said.