The spectral image that has haunted this presidential campaign finally surfaced last weekend on television with an attack ad of his own. All that was missing was the tag line: "I am Osama bin Laden, and I approved this message."

Bin Laden's campaign video was quickly dubbed the "October Surprise," but the real surprise is something different: It is that, despite warnings by U.S. intelligence that al Qaeda was planning a pre-election attack, it hasn't happened. Indeed, there hasn't been a terrorist attack on U.S. soil since Sept. 11, 2001, and the intriguing question is: Why not?

Perhaps someone in the bowels of the CIA knows the answer to this riddle, but I suspect they're mostly just guessing, like the rest of us. And for all the sparring between George Bush and John Kerry during the campaign over who could do a better job of fighting bin Laden, I doubt either of them could explain the al Qaeda puzzle.

The long-dreaded attack could still come at any time. But analysts suggest several possibilities: Al Qaeda may be much weaker than generally believed, bin Laden's ambitions may increasingly be political, and disruption efforts against him may be working.

The weakness of bin Laden's organization is clear to Peter Bergen, one of the few Western journalists to have interviewed him. "I don't think they have the people here in the United States to conduct operations. It's that simple," contends Bergen, who is now a fellow at the New America Foundation. This view is shared by Reuel Marc Gerecht, a former CIA operations officer who is now a fellow at the American Enterprise Institute. "He would have struck us by now if he could have," he argues.

Gerecht discounts a widely cited estimate that 18,000 to 35,000 terrorists passed through al Qaeda's training camps in Afghanistan. In rebuttal, he cites an interview he conducted in 1999 with bin Laden's chief Afghan rival, the Northern Alliance leader Ahmed Shah Massoud, who was assassinated two days before Sept. 11, 2001. He told Gerecht that he had faced at most 700 to 1,000 of bin Laden's Arab-Afghan fighters.

Bergen believes that the bin Laden of the latest video was attempting, in his own bizarre way, to join the presidential debates. It's the first time Bergen has seen him photographed without a gun at his side, for example. And in the full text of his comments, released by al-Jazeera on Monday, bin Laden talks about some unlikely themes, ranging from election fraud in Florida to Halliburton's contracts to the size of the U.S. budget deficit. He says his strategy is "bleeding America to the point of bankruptcy" by luring it into a costly war in Iraq.

A similar view of bin Laden as a political wannabe comes from Charles M. McLean, whose Denver Research Group analyzes thousands of sources of information in English, Arabic and other languages to frame what he calls "aggregated thought" about a topic. "Our systems are indicating that bin Laden's ultimate goal is to turn his movement into a political force within the Middle East," says McLean. He notes that in polls, bin Laden gets higher favorability ratings than George Bush or Tony Blair in Pakistan, Jordan and Morocco.

A final theory is that America and its allies have been successful in disrupting bin Laden's operations. The best account I've seen comes from George Friedman, who runs a private intelligence service called Stratfor and has just published a book called "America's Secret War."

Friedman argues that all the intelligence alerts and warnings, combined with arrests of suspected al Qaeda operatives around the world, have put bin Laden off balance. Every time the Bush administration issues a warning about a possible plot, bin Laden has to assume the worst. His operatives "could be captured without al Qaeda knowing it," Friedman writes in a recent analysis. "Worse, they could be captured, turned and released back into the field without al Qaeda knowing it. Even if the latter is unlikely, al Qaeda simply cannot be sure and, not being sure, they must abort the mission."

Given bin Laden's seeming weakness, one lesson for today's winner is a simple precept that British intelligence applied in its long war against a small but deadly network of IRA operatives: As you grind down your enemy, make sure you don't create more terrorists.

I erred in my column of Oct. 26 in describing a scoop last January by a Libyan journalist named Ashur Shamis. He was the first to report on his Web site a conspiracy by Libyan intelligence operatives to destabilize Saudi Arabia, but he didn't mention their plan to assassinate Crown Prince Abdullah. That was reported later by the New York Times.