A holiday anti-terrorism alert upgrade to code orange, besides being based on fresh intelligence, comes as a useful reminder of where the true danger lies. Saddam Hussein is safely in custody, but the far-and-away No. 1 terrorist threat is Osama bin Laden and his al-Qaida conspiracy.

He has clearly been the most wanted criminal fugitive for more than 10 years, since the first World Trade Center bombing, the attacks on two U.S. embassies in Africa, the attack against the U.S. warship Cole, and, worst of all, the Sept. 11, 2001, attacks on the World Trade Center and the Pentagon. And he and his gang are still at it. His chief deputy, Dr. Ayman al-Zawahiri, in a taped broadcast on Friday over the Arabic television network Al-Jazeera, said: “We are still chasing the Americans and their allies everywhere, even in their homeland.”

The Bush administration had reason to warn Sunday that the terrorist conspiracy might once again resort to using commercial aircraft as missiles. The White House and the U.S. Capitol were on their target list last time and doubtless are still there. Long fences around the Washington Monument grounds show rightful concern about another high-profile terrorism target.

American military intelligence demonstrated its skill and insight in tracking down Mr. Hussein. A special team of investigators devised a diagram charting hundreds of his relationships with relatives and supporters. They narrowed it down to a few trusted aides who sheltered him as he dodged from one hideaway to another. Finally the trail led to the remote farmhouse, where Mr. Hussein himself lay at the bottom of a spider hole.

Let’s hope that a similar manhunt, pursued with the same zeal and perspicacity, is in progress to catch Osama bin Laden. Mr. Hussein, evil as he was and thrilling as was his capture, was still just a part of the anti-terrorism campaign. No evidence has yet been found that he had anything to do with Sept. 11 or the other terrorist attacks. Osama bin Laden and al-Qaida are the threat, and they must be tracked down, caught and brought to justice.