America's warlords: up close with the U.S. military regional commanders who run the world.

• Author: Fallows, James
• Position: THE MISSION: America's Military in the Twenty-First Century by Dana Priest Norton & Co

THE MISSION: America's Military in the Twenty-First Century by Dana Priest Norton & Co., $26.95

WHEN PEOPLE SPOKE OF AN American "empire" in the 1990s, they mainly used the term as a metaphor. The Soviet Union was gone; formerly communist economies from Vietnam to Romania were competing to attract U.S. investors; American music, movies, and computer programs were being pumped out around the world. Ambitious young people decided that they needed to learn English--even, sacre bleu, the ambitious young people of France. Old Europe's sense of being left behind by resurgent America gave the most serious spur to continental unification since World War II. And even though U.S. troops were chronically involved in regional wars and peacekeeping operations, the real foundation of American dominance seemed to be its "soft power"--the impact of its world-leading universities, its dominant pop culture, its revived high-tech industries, its booming employment rolls, its open-market ideology, and its continued ability to attract and use talent from around the world.

One surprising implication of Dana Priest's The Mission is that even in the 1990s the foundations of empire were "harder" than they seemed. This is a loosely structured but fascinating and important book. While it draws few conclusions of its own, it provides vivid evidence about the contradictory effects of America's unmatched military power. On the one hand, there really is an empire, held together by expeditionary forces working in scores of countries around the world. On the other hand, there is also such a thing as imperial overstretch. Priest's accounts of the consequences of past military victories--in the Balkans, in Latin America, in the Middle East during the first Gulf War, and against the Soviet Union during the long Cold War--suggest the list of challenges the United States will face after a military victory in Iraq.

The organizing principle of the book--at least the one it starts out with--is the underappreciated idea that the real power in the military no longer lies with the chiefs of staff in the Pentagon. Instead it is wielded most dramatically by the regional commanders in chief (CinC) in the field. Priest--who has covered several wars and many years' worth of defense policy for The Washington Post--suggests at the beginning of the book that she will tell me story of the modern military through the story of these CinCs, pronounced "sinks."

The CinCs are in charge of all U.S...