Khaled Sheikh Mohammed Arrested in Pakistan

TOM BROKAW, anchor:

In the war on terror, the most encouraging news yet in the worldwide effort to crack the leadership of al-Qaeda. Khalid Shaikh Mohammed, the man believed to be the mastermind behind the 9/11 attacks, is in American hands tonight and so are his cell phones and laptop computer. We have two reports on this major breakthrough. We'll begin with NBC's Pete Williams.

PETE WILLIAMS reporting:

At the house in Pakistan where Khalid Shaikh Mohammed was arrested, officials tell NBC News, police and American agents found a potential intelligence windfall, his actual laptop computer. It's part of the reason officials throughout the US government hailed the arrest. Justice Department criminal chief Michael Chertoff:

Mr. MICHAEL CHERTOFF: History will record it as a landmark victory in the war against terrorism.

WILLIAMS: On that laptop, government investigators say, just what they were hoping for--rundowns on current al-Qaeda plans for terror attacks and the names of operatives willing to carry them out, including some potential terrorists thought to be in the US. FBI agents are now scrambling to follow up, acting on new leads almost the moment they're pulled from the computer. Agents say tonight they wish they'd had a few days to act before Mohammed's arrest became public, which tipped off al-Qaeda members that their identities might be compromised. Pakistani police felt so good about their role in the arrest of the number-three man in al-Qaeda that they took this humiliating picture of Mohammed moments after finding him, startling him awake in the middle of the night. An image, officials say, intended explicitly to contrast with the only other available photo taken years ago. But does the arrest make America safer? Some say yes because al-Qaeda's top planner is now out of action.

Mr. TOM RIDGE (Secretary of Homeland Security): We're going to get them one at a time, and we just did. And we got a big one this past weekend.

WILLIAMS: Intelligence experts say it also puts remaining al-Qaeda members on the defensive, making them less bold for now.

Mr. JOHN GANNON (Former CIA Deputy Director): You're going to be much more concerned about--about the ability of the United States and its--and its allies to--to get you much earlier on in the process.

WILLIAMS: Still, officials caution that al-Qaeda has become more flexible, allowing low-level operatives to attack without top approval. And some experts warn the arrest could provoke terrorists to attack in retaliation or to rush planned attacks to completion.

As for Mohammed himself, after three days of interrogation, officials say he isn't yet talking, but they believe he knows more than anyone else they've captured. So even if he reveals only part of what's in his head, that could still be a big break. Pete Williams, NBC News, Washington.