In his first few months in office, President George W. Bush has made a number of missteps. But he has shown bold and creative leadership on one subject: defense.

Bush has appointed a team of brilliant and experienced military experts, including Defense Secretary Donald Rumsfeld, Deputy Secretary of Defense Paul Wolfowitz, and Andrew Marshall, the legendary strategic thinker in charge of the administration's defense review. If they can overcome resistance in the Pentagon and Congress, the Bush administration will replace an obsolete American military with one adapted to the challenges of the 21st century. While the information revolution is changing the way we do business, shop and amuse ourselves, its equivalent in foreign policy, the revolution in military affairs, also known as the RMA, is on the verge of transforming the very nature of war and diplomacy.

The way we and most countries think about the military has changed little since World War II. Even the basic weapons in the military arsenal, like bombers and fighters and tanks, are modified versions of weapons introduced nearly a century ago.

The use of computerized, precision-guided missiles by the U.S. and its allies against Iraq, Serbia and Osama bin Laden has acquainted the public with these so-called "smart missiles." But few people other than military reformers realize yet how radically the missile is going to change the military.

For one thing, the Air Force in its present form is not long for this world. Crewed aircraft will be replaced by ever-more intelligent missiles and reconnaissance drones.

Tanks, which put the cavalry out of business only a few generations ago, soon will soon find themselves out of jobs. As missile technology spreads, tanks become easy targets -- and death traps for the crews inside.

In the future, human soldiers may be miles away from battlefields where high tech "silicon soldiers" such as smart missiles, drone aircraft, robot tanks and robot mines -- or even more exotic devices, like swarms of miniature machines -- struggle for control of territory. Troops may be sent only to occupy an area after these silicon soldiers have won the battle.

The missile revolution will transform war at sea as well as war in the air and on land. Defense contractors have plans for arsenal ships -- essentially, floating missile silos operated by skeleton crews. Thanks to advances in automation, less precious space on ships and submarines will go to crews, making more room for weaponry and advanced electronics.

Although a few visionaries in the Pentagon are prepared for the new ways of warfare, many of America's soldiers are about as pleased by the advent of the missile as America's horse soldiers were by the advent of the tank in the 1920s and 1930s.

Thanks to the RMA, an entire military way of life is about to become extinct. The age of mass armies, in which conscripted or professional soldiers live apart from the American mainstream in miniature cities with their own grocery stores and golf courses, quickly will come to an end.

Instead of the old mass military, we now need two new militaries.

One will consist of professional, highly-motivated expeditionary forces that can be deployed for years or even decades to hot spots like the Balkans and the Middle East.

The other military will consist of skilled technicians operating our silicon soldiers from a distance.

The U.S. Marines, specialists in low-intensity conflicts, provide a model for the flexible expeditionary forces of the future. The Army, though, may be obsolete. Many of the technicians who operate the robot arsenal of the future could be civilians, or at least have a quasi-civilian lifestyle, like those who work in our intelligence and diplomatic agencies.

Indeed, it would be easier to attract highly skilled and well-educated Americans into the military if a military career did not condemn them to a life inside a separate subculture with conservative ideas about feminism, homosexuality, adultery and divorce dating back to the era of the sailing ship.

To prepare America to fight its enemies in the new millennium, Bush's military reformers must must fight resistance inside the military itself. Unfortunately, the Bush administration unintentionally may have undermined its own laudable effort to modernize the Pentagon.

Creating a military for the missile age is going to cost money -- lots of money. By throwing away much of the budget surplus on unnecessary tax cuts that chiefly benefited the wealthy, Bush may have deprived Rumsfeld's reformers of the resources they need.

The Bush administration also has put too much emphasis on missile defense. Missile defense is a good idea, only as a supplement to a modern military strategy, not as a substitute for one. The public needs to hear more about arsenal ships for the Navy and less about SDI.

In the 20 century, visionary reformers in the U.S. military like Billy Mitchell, the prophet of air power, and George Patton, who saw the potential of the tank, were derided by the services and starved of funds for their experiments. Our nation paid the price at Pearl Harbor. Let's adapt our armed forces to today's challenges with today's technology, without waiting for an Information Age Pearl Harbor to force us into the future.