Extremists need enemies

It's far from clear why Muslim terrorists attacked civilians in Mumbai, but extremists need enemies. Most of all, when under pressure, they need to share their enemies and their hatreds with the populations that they hide among.

It's easy to stir up long-standing secular and sectarian enmities between India and Pakistan. They're never far below the surface.

Even a war of words between these two nuclear powers will rally Pakistanis to all things Pakistani and all things Islamic, even terrorist organizations. That benefits all the terrorist groups that thrive on chaos.

The U.S. has enough electronic surveillance to know already where these terrorists attacked from. The NSA knows who took their calls in Waziristan. Whether we'll ever know is another question.