If he sings like a bird under the hot lamp of interrogation, Al Qaeda's top operational leader, Khalid Shaikh Mohammed, could reveal the minutest details that would help the US blow open his terrorist network, especially the so-called sleeper cells in the US and Europe.
His capture in Pakistan on Saturday is the most successful victory in President Bush's war on terrorism since the US liberated Afghanistan soon after Sept. 11 and scattered Al Qaeda's leaders.
Even if Mr. Mohammed doesn't talk, Al Qaeda has lost its main architect, one whose dark visions and effective command of lesser radicals led to many of the big terrorist attacks over the past decade, including Sept. 11. The capture, too, of his computers and papers, along with two compatriots, will force Al Qaeda to further scatter and hide, delaying its attempts to recruit and rebuild.
Among the lessons to be learned in his arrest is that the US can bring down Al Qaeda even as it fights conventional wars. US intelligence agencies can also now be judged to be effective in their electronic snooping and in developing good relations with other countries. Pakistan has helped the US capture over 400 Al Qaeda members. So far, a third of the network's leaders have been captured or killed worldwide. And it also helped that the US offered a $25 million reward for information on Mohammed's hideout.
Al Qaeda still has the means for major strikes, and its two ideological leaders, Osama bin Laden and Ayman al-Zawahiri, remain at large. But the arrest of the man who claimed to be the mastermind of the Sept. 11 attacks should reduce much of the public fear that Al Qaeda only hopes to create and increase. And this success creates a momentum of confidence that can help the US win this war as much as anything.