Change means that al-Qaeda poses a new form of threat to the world
Key leaders have been killed, but terrorism experts warn the organisation may be stronger after forging ties with like-minded groups
The al-Qaeda organisation is now more decentralised, but it is unclear whether the terrorist network is weaker and less likely to launch another major attack against the US, as President Barack Obama says, or remains potent despite the deaths of several leaders.
Obama said in his foreign-policy speech last week that the prime threat came not from al-Qaeda's core leadership, but from affiliates and extremists eyeing targets in the Middle East and Africa, where they were based. He said this lessened the possibility of a major attack on the United States.
"But it heightens the danger of US personnel overseas being attacked, as we saw in Benghazi," he said, referring to the September 2012 attack on a US diplomatic outpost in Libya that killed the ambassador and three other Americans.
Experts argue that this restructured al-Qaeda is perhaps even stronger than it has been in recent years, and that the potential for attacks on US soil endures.
David Sedney, former deputy assistant secretary of defence for Afghanistan, Pakistan and Central Asia, said: "We have never been on a path to strategically defeat al-Qaeda. All we've been able to do is suppress some of its tactical abilities.
"But strategically, we have never had an effective way of taking it on. That's why it continues to mutate, adapt and evolve to get stronger."
Decentralisation did not mean weakness, he said.
"I think Americans think al-Qaeda is no longer a threat. That Osama bin Laden's death means al-Qaeda is not a big thing any more," Sedney said.
He believes the group is gaining strength in Pakistan, is stronger in Iraq than it was three or four years ago and is stronger in Syria than it was a year or two ago.
"This is a fight about ideology. Al-Qaeda is not this leader or that leader or this group or that group," he said.
The experts say al-Qaeda today looks less like a wheel with spokes and more like a spider web stringing together like-minded groups. But they believe there are several reasons that those who track the group warn against complacency.
While bin Laden was killed and his leadership team heavily damaged by US strikes in Pakistan, the withdrawal of American forces in Afghanistan will dry up field intelligence and restrict the effectiveness of US counter-terrorism operations. There is a worry that a pull-back could allow al-Qaeda to regroup.
Moreover, they worry about the many thousands of foreign fighters flocking to the civil war in Syria, which has emboldened the al-Qaeda breakaway group known as the Islamic State of Iraq and the Levant to expand its cross-border operations into neighbouring countries such as Iraq.
US officials are also concerned about Westerners who have joined the Syrian fight because they may be recruited to return home and conduct attacks.
Katherine Zimmerman, of the conservative American Enterprise Institute, said that when the US counter-terrorism strategy was conceived, it was thought that if al-Qaeda's core leadership was dismantled or killed, then affiliated groups would simply become localised threats in their home regions.
Zimmerman, who specialises in the Yemen-based group, al-Qaeda in the Arabian Peninsula and its affiliate in Somalia, al-Shabab, said that at that time, there wasn't a network of connections among all the groups.
"As the network has become more decentralised, it has become much more reliant on these human relationships and the sharing of resources, advice and fighters, which means that you no longer need bin Laden sitting in Pakistan dispersing cash to various affiliates," she said.
"They have developed their own sources ... You can't simply pound on part of the network and expect to see results."