A PRESIDENT'S POWER as commander in chief, or highest ranking official, of the U.S. military makes him the most formidable military opponent in the world. The president and his secretary of defense, both civilians, are followed in the chain of command by the joint chiefs, or heads of the various service branches. These include the army, navy, air force, and marines. In times of war or military emergency the president discusses strategy with the defense secretary and joint chiefs. But, as commander in chief, the president has the final word on the deployment and use of all troops, equipment, and weapons, including the country's huge nuclear arsenal. Presidents have used this vast military authority not only to defend the country, but also to enforce various kinds of national or international policy.

Yet the president does...