Bucharest, Romania ? No matter how much Russia hates it, the U.S. now has a clear track to build its long-range missile defense system in Europe.

The crucial go-ahead came Thursday from the Czech Republic, where a vital radar site would be located.

NATO leaders added their unanimous backing for the idea at a European summit, all but sealing the controversial deal just before President Bush’s weekend meetings with Russian President Vladimir Putin. Putin has harshly criticized the proposed system, portraying it as a threat to Russia, virtually on its doorstep.

Beyond the immediate dispute, the Czech accord and the NATO endorsement marked an important moment in the long history of U.S. efforts to persuade allies of the merits of missile defense.

At Thursday’s NATO session the leaders declared that the proposed U.S. missile defense shield for Europe would make a substantial contribution to the region’s security and that Russia should stop criticizing it, Secretary of State Condoleezza Rice told reporters afterward.

The intent is to combine the U.S. system, which is meant to shoot down long-range missiles, with one run by NATO that could defend against shorter-range missiles that are more of a worry to countries like Turkey, Greece, Romania and Bulgaria. Because of geography, they face a nearer-term threat from Iranian missiles.

The Russians insist it’s really a scheme to undermine their own missile force.

The Czech radar would be linked to a set of 10 interceptors that the U.S. wants to place in Poland. The Poles have not yet agreed.

Poland has insisted on U.S. military aid as part of an agreement, and Bush recently indicated that was possible.

The Pentagon wants to have the Polish and Czech sites in running order by about 2012.

Illustrating how attitudes have changed, Rice said that when Bush attended his first NATO summit in 2001 “perhaps only two allies gave even lukewarm support for the notion of missile defense.” She described Thursday’s NATO statement as a “breakthrough agreement” that isolates Russia in its adamant opposition.

The NATO leaders said they agreed with the broader point that ballistic missiles pose an increasing threat to Europe.

At their meeting scheduled for Sunday in the Black Sea resort city of Sochi, Bush and Putin are expected to agree that missile defense is one of many high-priority topics for their successors. But it appears unlikely that Putin, who steps down in May, will suddenly embrace a project he considers to be provocative.

The Czechs agreed to host an American radar that would be used to track the flight of missiles headed toward Europe from the Middle East. It would, in effect, be a set of eyes needed to guide missile interceptors to their target – long-range ballistic missiles of the sort Washington believes Iran is developing.