Warsaw, Poland ? The United States and Poland signed an agreement here Wednesday to place parts of a U.S. missile defense system on Polish territory, finalizing a long-negotiated deal in the face of Russian warnings that Poland would become a potential target for attack.

At a signing ceremony with the Polish political leadership, Secretary of State Condoleezza Rice said the system, which will place 10 missile interceptors and more than 100 U.S. troops here, will “help us to respond to the threats of the 21st century.”

The agreement, suddenly concluded after 18 months of negotiations, came at a time of heightened tensions between Russia and the NATO alliance over the war in Georgia. NATO on Tuesday said it will suspend “business as usual” with Russia after its invasion of its southern neighbor.

Despite pledges from Moscow that it would withdraw its troops, Rice said there was little sign Wednesday that the Russians are ending what NATO has called their “occupation” of Georgia. German and French officials voiced similar charges Wednesday that there was no sign that a withdrawal had begun in earnest.

In a continuation of tit-for-tat rhetoric over Georgia, Moscow said Wednesday that it would “freeze all military cooperation with NATO and allied countries,” according to a statement by the Norwegian Defense Ministry reported by the Associated Press. Norway, a NATO member, said it had received a telephone call from the Russian Defense Ministry.

The Polish-based interceptor rockets, along with a radar installation to be based in the Czech Republic, will provide a European base for a defense system the Bush administration has insisted is not aimed at Russia but at “rogue states” such as Iran.

John Rood, undersecretary of state for arms control and nonproliferation, negotiated the Polish deal, and said there was no direct correlation between the timing of the missile defense agreement and the situation in Georgia. But “obviously,” he said, it was finalized within a “certain environment.”