HUMBLED BY THEIR dependence on American might in Kosovo, Europeans are pressing ahead to develop their own defense structure. Last month's European Union summit promised closer military ties. On Tuesday, an Anglo-Italian summit urged their arms makers to pursue closer integration. The Europeans want the muscle to deal with future Kosovos by themselves; they also want this muscle to be supplied by their own arms makers. These ambitions worry some people in Washington. But why? One way or another, Europe will remain dependent on America, because its dual ambitions are incompatible.

Europe's defense industry does not make cruise missiles, top-of-the-range satellites, AWACS surveillance aircraft or long-range military transport aircraft. In the short term, Europe has to choose. If it wants the equipment to fight a Kosovo-style war, it must shop in America -- and accept dependence on Uncle Sam for maintenance and spare parts. But if Europe wants to nurture its own arms makers, it will buy plenty of guns and tanks, but not much of the high-tech gear that makes America militarily indispensable.

The issue is not whether Europe will outgrow dependence on America. It is whether Europe can become a more vigorous ally. At present, Europe's competing military establishments waste millions on expensive gear from dozens of tiny firms; mergers would create economies of scale and free up money to plug high-tech gaps. At the same time, the profusion of suppliers makes for incompatible equipment and battlefield inefficiency.

By this logic, the Pentagon has encouraged consolidation in America's defense industry: Lockheed Corp. and Martin Marietta merged in 1995, Boeing and McDonnell Douglas in 1997. Yet when Europeans belatedly head down the same path, the Pentagon says it is worried by a pending merger between British Aerospace and GEC-Marconi, two British companies, even though this marriage would not alter Europe's dependence on America for high-tech. The Justice Department's anti-trust investigators are looking into the deal, even though the notion that the resulting British powerhouse would stifle competition seems strange: Both Lockheed Martin and Boeing would remain still bigger. Rather than quibbling over mergers of this kind, the administration should join Europe's leaders in encouraging them.