their cause's profile and attracting recruits and financing.

WASHINGTON — If al-Qaida turns out to have been behind yesterday's bombings in London, as British officials suggested, it would be further evidence of the changing face of the extremist group, terrorism analysts said.

Al-Qaida, they said, is global, opportunistic, fragmented — and still very potent. The group's battle against Western society is both a war and an evolving propaganda campaign.

Since 9/11, the pace of al-Qaida-sponsored attacks has quickened. They are now occurring globally at a rate of approximately once every three months, compared with less than once a year prior to 2001, according to Brian Jenkins, who has studied terrorism for more than three decades.

At the same time, the number of casualties in each attack has been lower, he added.

These newer, smaller attacks are part of an emerging strategy by al-Qaida, said Michael Scheuer, a former head of the CIA's Osama bin Laden unit and better known as the author of "Imperial Hubris," which critiqued the government's anti-terror policies.

The older part of the al-Qaida strategy, the more massive, 9/11-style attacks, often involved many years of planning. The second, more recent phase, is part of a violent campaign against U.S. allies that al-Qaida has vowed to attack.

"This is a whole different campaign," Scheuer said of attacks in Madrid, in Bali and elsewhere "This is designed to attack our allies."

Now more a brand than a tight-knit group, al-Qaida has responded to four years of intense pressure from the United States and its allies by dispersing its surviving operatives, distributing its ideology and techniques for mass-casualty attacks to a wide audience on the Web, and encouraging new adherents to act spontaneously in its name.

As in the Madrid rail bombings, these looser adherents sometimes copy al-Qaida's signature method of simultaneous explosions against symbolic or economic targets, an approach repeatedly advocated by al-Qaida founder bin Laden in his recent recorded speeches. Al-Qaida's evolution from headquarters-planned conspiracies toward diffuse ideological incitement and tactical support is consistent with bin Laden's long-stated goal.

For years, bin Laden has emphasized his desire to be remembered as a vanguard, an inspiring leader whose spark would light a spreading fire among all the world's Muslims, causing them to revolt en masse against Christians, Jews and their allies in the Middle East. During the past year, the thinking of bin Laden and other key fugitive leaders — as communicated in taped addresses and on password-protected Internet message boards — has been influenced by the course of the war in Iraq. Last November, Iraq-based terrorist Abu Musab al-Zarqawi pledged allegiance to bin Laden, and by doing so created at least the appearance of a unified al-Qaida approach to the war.

Indeed, al-Zarqawi's pledge to bin Laden has offered a model of the new kind of al-Qaida outsourcing. "From al-Qaida's point of view, it makes it look like they're in on the biggest action going right now in Iraq," said a former U.S. intelligence official, speaking on condition of anonymity. "From Zarqawi's point of view, it's brand recognition — you're a franchisee."

Both bin Laden and al-Zarqawi have emphasized two prominent themes in their approach to the Iraq war: driving a wedge between the United States and its allies, and bleeding American and allied economies.

Bin Laden and some of his lieutenants have strongly emphasized economic issues related to Iraq in recent postings and speeches. In his videotaped speech to the American people last November, on the eve of the U.S. election, he boasted of "the success of the bleed-until-bankruptcy plan."

In waging these smaller attacks, Scheuer said, al-Qaida is trying to turn the people of those countries against their U.S.-aligned government. If the attacks were much larger, he said, they would risk rallying those countries around their governments.

But that should not comfort Americans, he cautioned.

"They're saving the big one for us. We are their main enemy," he said. "The people who assume this is all they can do are kind of whistling past the graveyard."

Other analysts said there is a perception, deserved or not, that the United States is harder to penetrate, so al Qaeda-inspired jihadists are going elsewhere — for now.

The smaller attacks also keep the group and their cause in the public eye, said Jenkins.

"In the meantime, it is imperative for them that they continue operations not simply for what it does to us, but for what it does for them," Jenkins said, namely, attracting new fighters and financing.

The group that claimed responsibility for the bombings, "Secret Organization of al-Qaida in Europe," is unknown to analysts who track terrorism, and government officials have not yet identified the perpetrators of the attacks. This new organization would fit the post-9/11 trend of al-Qaida's becoming a movement of loosely affiliated, ad-hoc groups.

The European terror infrastructure may actually be expanding. Freshly trained terrorists, or jihadists, appear to be returning to Europe from the war in Iraq, said David Kay, former chief U.S. weapons inspector in Iraq. Thomas Sanderson, deputy director of the Transnational Threats Project at the Center for Strategic and International Studies in Washington, has spent the past several months researching Kay's concern.

"There's no doubt about it that there could be a connection" between the London bombings and the Iraq-trained jihadists migration to Europe, he said. He cautioned, however, nothing can be said conclusively until more is known about who was behind the attacks.

"I do not really believe there is such a thing as al-Qaida, the organization; there is al-Qaida, the mindset," said Yosri Fouda, senior investigative reporter in London for the al-Jazeera satellite television network, the only journalist known to have interviewed Sept. 11 planners Khalid Sheikh Mohammed and Ramzi Binalshibh. "This is what I find much scarier. Your ability to predict is reduced to a minimal level."