LONDON – Some think he is dead, others think he is hiding because he is scared of being killed. Whatever the reason for the strange disappearance of Osama bin Laden, not seen alive since his last mocking video statement a year ago, he is no longer the face of the global jihad against the West.

The Jordanian responsible for some of the worst atrocities in Iraq, Abu Musab al-Zarqawi, has become the hero of the hour on militant Islamist Web sites.

Western intelligence sources believe that he now receives most of the donations and recruits for the jihad against America and its allies. And they fear that he is already planning to expand his attacks to the Arab world and Europe.

“Zarqawi is the world’s no. 1 terrorist. There is every indication that he thinks he has outgrown Iraq,” a Western source familiar with intelligence reports said. “It is bound to happen sooner or later.”

And while Mr. bin Laden performs his vanishing act, his “deputy,” Ayman al-Zawahiri, also performs ever more frequently as Al Qaeda’s chief television propagandist.

The Egyptian doctor, regarded by many as the real ideological force of Al Qaeda, has made at least six video and audio broadcasts this year – discussing everything from Iraq’s elections, the London bombings, and, most recently, the Kashmir earthquake.

This has puzzled the professional Al Qaeda watchers. “There are three main theories,” a Western security source said. “Perhaps bin Laden is acting as president, who only speaks on big ‘state’ occasions, while Zawahiri is the prime minister who deals with day-today business.

“Perhaps bin Laden is alive but too ill to show on television without demoralizing his supporters.

“Or perhaps he is dead. But this is unlikely – if he had died, we would have heard about it.”

Mr. bin Laden was last seen alive in a video recording addressed to the American people ahead of last November’s presidential election.

Then he taunted President Bush, saying: “It was easy for us to provoke this administration and pour it into perdition.” He also boasted of “the success of our plan to bleed America to the point of bankruptcy.” A letter in the name of Mr. bin Laden appeared on the Internet last December, urging Arabs to overthrow “apostate” Arab rulers.

Mr. bin Laden has previously been out of public view for months at a time. Speculation about his fate is swirling.

One Arab intelligence source argued months ago that Mr. bin Laden was probably dead. A Pakistani newspaper reported recently that Mr. bin Laden had died last summer and was buried in the Afghan city of Kandahar. An Indian paper claimed that he might have died in the Kashmir earthquake.

Over the weekend Defense Secretary Rumsfeld attributed Mr. bin Laden’s low profile to his fears for his safety as American and Pakistani forces hunt down Al Qaeda members.

Whether or not Mr. bin Laden is dead, his network has been permanently changed. Members of the old Afghan-based “core” of leaders around Mr. bin Laden and Mr. Zawahiri have been killed, captured, or scattered to the point where they find it difficult to mount a major attack on the West.

Instead they focus on spreading the ideology that inspires others to attack.

“Think of it as a McDonald’s franchise,” the security source said. “Bin Laden and Zawahiri own the copyright to the golden arches, but Zarqawi is the one selling the hamburgers – and very successfully.”

The shift is most visible from a recent letter from Mr. Zawahiri to Mr. Zarqawi, intercepted by America . If genuine, the Al Qaeda franchise-owners are awed and appalled by the Zarqawi product.

Mr. Zawahiri pleaded for money, bemoaned the danger posed by the Pakistani army, and gave the impression of being partly cut off from events. However, he knew enough about Iraq to rebuke Mr. Zarqawi for the wholesale murder of Shias and the grisly beheadings of hostages broadcast on the Internet.

Recalling that he “tasted the bitterness of American brutality” when his wives and children were killed in an American bombing in Afghanistan, Mr. Zawahiri argued: “Despite all of this, I say to you: We are in a battle, and more than half of this battle is taking place in the battlefield of the media.”

The problem for western counter-terrorist officials is that regardless of what happens to Messrs. bin Laden, Zawahiri, or Zarqawi, it may now be impossible to eradicate their ideology. As Mr. bin Laden once put it: “This will be nothing to do with the poor slave bin Laden, whether dead or alive. With God’s grace, the awakening has begun.”