Congress moves to inject some sense into the Bush administration’s favorite defense project.

THE STILL-GROWING diplomatic storm over the Bush administration’s attempt to install missile defense bases in Europe is mostly Russia’s doing. Vladimir Putin has skillfully and cynically used the administration’s plans to deploy 10 interceptors in Poland and a radar in the Czech Republic as a way to stir up trouble in NATO and to justify new steps in Russia’s increasingly belligerent foreign policy — such as moving toward the renunciation of a treaty limiting conventional military forces in Europe. The administration is right to call Mr. Putin’s broadsides “ludicrous.” Yet that doesn’t mean its anti-missile strategy is sensible.

The Pentagon has been chastised repeatedly by Congress, government watchdogs and its own expert auditors for rushing the deployment of missile defense systems before they have been adequately tested or a genuine threat has materialized. Yet despite promising to learn from its mistakes, the administration is repeating them in Europe. It opened bilateral negotiations with the Polish and Czech governments on missile bases without adequately consulting other European allies or coordinating the proposed system with NATO’s own missile defense projects. It asked Congress to appropriate more than $300 million for the project next year, even though the threat it is aimed at — an Iranian missile capable of reaching Europe — isn’t expected to materialize until 2015.

Most troubling, the administration elected to press ahead even though the “midcourse” system, designed to shoot down missiles while they are still beyond Earth’s atmosphere, has not proved itself in testing. Only one successful test of the interceptor has been conducted since 2002, and that was under controlled conditions that wouldn’t be present in a real attack. Two more are planned for the coming months, but even if they succeed, the system will be far from reaching the standards usually required of weapons systems before they are deployed.

Politics is the most plausible explanation for this costly rush. The administration was determined to lower the first interceptor missiles into silos in Alaska before the 2004 election; now it appears determined to pour concrete in Europe before 2008. This time, though, Congress is more likely to step on the brakes. Democratic Rep. Ellen O. Tauscher of California and chairwoman of the House subcommittee handling missile defense, says she has support from both parties to eliminate funding for construction in Poland in a markup today. She also plans to introduce language that would give the Pentagon’s Operational Test and Evaluation office, which judges the readiness of all other weapons systems, control over missile defense testing for the first time in six years.

Those are prudent moves. Ms. Tauscher rightly says she is open to building a missile defense base in Europe eventually; the partisan debate over whether the United States needs a defense against missile attacks is long over. Russia’s attempts to obstruct the process should be exposed for what they are — a return to Cold War diplomacy. But there is no reason to embrace the administration’s rush to failure. More time and effort need to be devoted to winning European support for the system and integrating it with NATO’s plans. Europeans should be asked to share the expenses of a project that could eventually cost $4 billion. And no more interceptors should be deployed until the Pentagon’s independent testers can confirm that they are likely to work. Congress can play a valuable role by ensuring that this high-flying defense project is tethered, at last, to realities on the ground.