Osama bin Laden is dead. Now it is time for the peace dividend. That’s a phrase you may remember from the early 1990s, when Soviet Communism, the big existential threat of the second half of the 20th century, collapsed. Today, America needs a peace dividend even more than it did 20 years ago. But cashing it in will be a challenge.

That’s partly because, as in 1991, the death of Bin Laden should be the trigger for a much broader rethinking of U.S. foreign policy. That will be tough to initiate. Since 1941, the United States has defined its role in the world largely in opposition to an unambiguously evil foreign enemy: first the Axis powers, then the Soviet bloc, and, for the past decade, Al Qaeda and its allies.

This kind of foreign policy was expensive — but it had the virtue of intellectual and moral clarity. One measure of how comforting this Manichean approach was came from the speed with which the threat posed by Al Qaeda came to be equated with the dangers of Soviet Communism.

Recall an important essay published in January 2002, by Daniel Pipes, titled “Who is the Enemy?” Pipes is literally, as well as figuratively, a son of the Cold War warriors — his father is Richard Pipes, the eminent Russian historian and one of the seminal theorists of totalitarianism and its baleful international impact.

For Pipes fils, radical Islam was the 21st century’s version of Soviet totalitarianism, and it was every bit as dangerous. In his Commentary essay Pipes approvingly quoted the view of Willy Claes, secretary general of NATO in the mid-1990s, that “not only did militant Islam pose the same kind of threat to the West as Communism before it, but the scale of the danger was greater.”