Our finest foreign-policy minds have been abuzz lately trying explain how and why the U.S. and its NATO allies are, as a recent Newsweek International cover has it, "Losing Afghanistan." But no need for deep thoughts here: The largest part of the problem is neighboring Pakistan.

In September, the Pakistan government of Pervez Musharraf agreed to abandon its North Waziristan province -- which shares a long border with Afghanistan -- to the de facto rule of its "tribal elders" and the Taliban and mujahadeen terrorists they harbor. Since then, as Barnett Rubin observes nearby, the number of cross-border raids into Afghanistan has risen threefold.

It's true that the agreement the Pakistan government signed with these elders explicitly forbids such raids. But General Musharraf surely knew that the Taliban would not keep idle in Waziristan for long, especially since he also agreed to the release and pardon of all Taliban prisoners and the return of their confiscated weapons.

From day one in the war on terror, the Bush Administration has said it would make no distinction between terrorists and those who harbor them. So far, Mr. Musharraf has earned an exception to this rule by helping to capture al Qaeda suspects early on, and then by pleading that his government cannot control its unruly tribal areas. But then he cannot also refuse to allow NATO troops and U.S. Predator missiles to do the job for him.

We don't know what General Musharraf promised President Bush and Afghan President Hamid Karzai during their recent conclave in the White House. But we hope it was more tangible cooperation than we have been seeing of late. Sovereignty has responsibilities, and General Musharraf is not exercising them