President Bush’s plan to deploy missile defenses in Central Europe will reduce U.S. security, not enhance it. Installing radar for tracking incoming missiles in the Czech Republic and anti-missile interceptors in Poland could do more harm than good.

Ostensibly, the European radar and interceptors are aimed at the future threat of nuclear-armed Iranian missiles. But Russia suspects  perhaps with good reason  that the real purpose of the deployments is to cement the security guarantees the United States has given to the two former Russian allies. In addition, Russia fears, also with justification, that the missile defenses could be augmented someday and used against Russian missiles. Moscow’s vitriolic threat to pull out of an arms-control agreement in protest is a warning the United States should heed.

After the Warsaw Pact dissolved and the Soviet Union collapsed, a weak Russia rolled over during two rounds of NATO expansion into what used to be Eastern Bloc territory. A stronger Russia now regrets such conciliatory policies because they have left the country feeling encircled. In short, the Russian bear is now tired of having its nose pushed in the dirt and is growling back.

Even if a missile-defense system can be made to work  still an open question after more than 20 years of research and development, costing many billions of dollars  the United States needs to ask whether the risks it would create outweigh the risks it conceivably would reduce. And the greatest risk of all is the possibility that it could ensnare the United States in an unnecessary conflict with a nuclear-armed Russia.

The problem with even a working missile defense has always been that an adversary can more cheaply build decoys and other countermeasures, or even additional missiles, to overcome or defeat an expensive and limited defense system. Faced with such defenses, Russia and Iran could both adopt some or all of these responses, triggering a new arms race.

The United States and Russia have been reducing their nuclear arsenals, but a U.S. missile-defense deployment, especially in Europe, could reverse that trend.

The sobering truth is that the potent U.S. nuclear arsenal is still the best way to deter adversaries from a nuclear attack on the United States. Deterrence is a better, safer, and cheaper alternative than missile defense.

Furthermore, as a price for allowing the deployment of U.S. missile interceptors on its soil, Poland is demanding enhanced U.S. guarantees of protection from Russia.

But if the interceptors are designed to protect Poland and other European countries from Iranian nuclear missiles, why should the United States have to promise Poland favors to win the right to do it another favor?

Besides, what more could Poland possibly want than the already existing U.S. promise under the NATO treaty to defend Poland from outside attack? The Czech Republic will probably also want a payoff to gain enhanced security from Iranian missiles.

Small nations have a history of manipulating their protectors. They appeal to the protector’s desire to be the “Big Man (or Woman) on Campus.”

In the past, Japan has done so when demanding trade concessions from the United States as the price for allowing the United States to retain military bases in Japan, which protect that country. The United States foolishly has agreed to meet Japan’s demands, just as it probably will to win Czech and Polish support for missile-defense deployments in their countries.

It is sad to see the United States beg and give payoffs to European allies to assume an even greater burden in protecting them, while pursuing policies that could damage relations with Russia and fuel a possible arms race. Plans for U.S. missile defenses should be scrapped.