Monday's suicide attacks in Saudi Arabia suggest al-Qaeda's scattered remains can still inflict considerable damage on the US and its allies, experts say.
The Saudi bombings suggest al-Qaeda is no spent force
Counterterrorism specialists acknowledge that since the 11 September attacks, the Bush administration's war on terror can claim notable successes.
But both the US and the Saudi governments believe Osama Bin Laden's group carried out the bombings in Riyadh, suggesting it still has committed followers.
A third of al-Qaeda's top leaders and more than 2,000 suspected rank-and-file members have been captured in the past 20 months.
And more than $125m of the group's finances have been frozen, and worldwide intelligence gathering has dramatically improved, BBC security correspondent Frank Gardner says.
But a weakened, more dispersed al-Qaeda is by no means a spent force.
"After losing their Afghan bases, many [members] have fanned out across the world, regrouping in countries like Saudi Arabia," our correspondent says.
Sinews of war
The London-based International Institute for Strategic Studies (IISS) shares this assessment.
In an annual report issued this week, IISS warns that Osama Bin Laden's organisation is today "more insidious and just as dangerous" than it was in the run-up to 11 September.
The Afghan war removed its centralised command and forced the leadership to regroup in areas where it is much more difficult to direct operations, says Jonathan Stevenson, the author of the report.
"From an offensive point of view, the Afghanistan operation had a positive counter-terrorism effect," he says.
But Mr Stevenson adds: "From a defensive point of view, I think that it has made al-Qaeda harder to find.
"And in some ways they are better off without Afghanistan, because of course it deprives al-Qaeda's adversaries of any kind of really robust military option."
Gary Samore, also of IISS, said Osama din Laden's cause still enjoys "a fair amount of public support" in Arab and Muslim countries.
"Presumably that will allow them to continue to get financial support and recruits to carry out suicide attacks in the future."
Al-Qaeda 'a beehive'
Al-Qaeda affiliates do not need very much support to operate.
Bali bombing: Carried out by alleged al-Qaeda sympathisers
According to Michael Chandler, a security expert at the United Nations, attacks like the Riyadh bombings do not cost huge sums of money.
"They (militants) are able also, from cells that have been broken up, to survive on methods of self-funding that we have come across, with credit card fraud, petty crime, and drug money," Mr Chandler said.
Another expert, Rohan Gunaratna Mr Gunaratna - author of Inside al Qaeda, Global Network of Terror - compared the group to a beehive that had been kicked.
"If you attack it what happens? The bees are dispersing and they are finding new queens," he told Reuters.
Mr Gunaratna gave the example of South-East Asia's Jemaah Islamiah - the group blamed for last October's bombing in Bali.
"The politicised and radicalised segments of the Muslims
are feeling the need to wage jihad [holy war] in support of
their suffering brethren," he says.