Pushed to the brink of collapse in its traditional strongholds, al-Qaida has staged an unlikely but limited recovery over the past year through affiliates that have taken root in chaotic environments awash in weapons and beyond the reach of the U.S. military and CIA drones.
The groups have taken advantage of political tumult in North Africa and the Middle East, carving out enclaves in Mali, Syria and other locations that have given a previously gasping organization new breathing room.
The emerging offshoots have altered the composition of the terrorist network, scrambling its structure and complicating U.S. assessments of the threat that al-Qaida represents.
U.S. officials said the terrorist network's core in Pakistan and its ability to carry out large-scale attacks in the United States have been all but demolished, leading to a shift in focus to emerging threats elsewhere.
Recent attacks on U.S. facilities in Libya and a natural gas complex in Algeria, combined with the growing strength of an affiliate in Syria, have drawn attention to the lethal potential of an increasingly atomized al-Qaida network, officials said. And though the targets of the groups have largely been regional, their multinational memberships and adherence to al-Qaida's ideology have heightened concern that the violence could eventually spread.
The newer groups have more diverse memberships, abundant access to weapons and a willingness to collaborate, a senior U.S. intelligence official said. The official, like others interviewed for this article, spoke to the Washington Post on the condition of anonymity to talk freely about ongoing counterterrorism policy.
The shifting complexion of al-Qaida has created new counterterrorism challenges for President Barack Obama, who relied heavily on CIA drone strikes and clandestine missions by U.S. special operations forces to destroy large pieces of the al-Qaida network and kill its founder, Osama bin Laden, and other leaders in Pakistan.
U.S. officials said Obama's options are more constrained in North Africa and the Middle East, regions where the United States has fewer intelligence resources and has seen staunch counterterrorism allies, such as former Egyptian President Hosni Mubarak, driven from power.
In the short term, the affiliates provide new justification for the Obama administration's efforts to turn elements of its counterterrorism policies, including kill lists and drone bases, into fixtures for a fight expected to last another decade or more.
The U.S. military recently disclosed plans to build a drone base in the West Africa country of Niger to conduct surveillance flights over neighboring Mali, where al-Qaida offshoots seized control of parts of the country. U.S. officials have not ruled out using the base for armed drones, but for now they plan to rely on regional allies and France to contain the militants.
But as the war on al-Qaida moves into its second decade, the evolving nature of the threat raises more fundamental issues for the United States. Among them is whether the scale of the counterterrorism campaign is still warranted when its initial objective — the destruction of the core leadership organization that killed 3,000 Americans in the Sept. 11, 2001, terrorist attacks — has largely been accomplished.
U.S. officials said al-Qaida's franchise in Yemen on the southern tip of the Arabian Peninsula remains capable of — and committed to — carrying out attacks in the United States. Beyond Yemen, U.S. efforts are aimed largely at countering potential threats from groups that have not attempted transnational attacks, as well as a post-Sept. 11 determination to deny any node of al-Qaida a haven like the one its founders exploited in Afghanistan.
After bin Laden was killed in May 2011, senior U.S. officials including Defense Secretary Leon Panetta described the group as being on the verge of strategic defeat. Since then, a series of unexpected developments have extended the network's life span.
In particular, al-Qaida franchises have gained strength in regions touched by the Arab Spring. The popular uprisings that toppled autocratic governments across the Middle East also weakened the grip of security services that had kept extremist forces in check. Civil wars in Syria and Libya provided local militants with weapons, experience and popular legitimacy.
"What we're seeing in North Africa and Syria is an unfortunate result of the Arab Spring," said Seth Jones, a Rand Corp. analyst and former consultant to the Pentagon on counterterrorism.
Islamists in those countries are only nominally tied to al-Qaida, and most are focused on local causes. But their resurgence threatens Western interests in the region and perhaps beyond, Jones said.
Western governments already are warning of increased threats to embassies, businesses and tourists in the region. In France, where 10 percent of the population is of North African descent, security officials are bracing for the possibility of retaliatory strikes in response to its military action in Mali against militants linked to al-Qaida in the Islamic Maghreb, the affiliate in North Africa's Sahara and Sahel.
The Arab Spring "freed up people, resources and energy," while attracting foreign jihadists who gave local organizations a more international character, said Mike Shurken, a former CIA analyst.
"We're seeing evidence of internationalization of these local groups, particularly AQIM," Shurken said. "They are evolving rapidly, and perhaps finally becoming the thing that people were fearing: a group with an international agenda."
Among U.S. counterterrorism officials, a surging al-Qaida affiliate in Syria is a source of particular concern. The group, Jabhat al-Nusra, is backed by al-Qaida's branch in Iraq and has become one of the most potent groups in a broader insurgency against Syrian President Bashar Assad.
Al-Nusra, as it is known, was linked to suicide attacks on Syrian security installations last year that also killed dozens of civilians. Unlike rival groups, it has called attention to its al-Qaida ties and is thought to have attracted as many as 10,000 fighters.
Its short-term objective — the ouster of Assad — puts it in uncomfortable alignment with U.S. interests. But U.S. intelligence officials said they are gravely concerned that al-Nusra militants, including some who hold Western passports, might move elsewhere in the Middle East or into Europe when the rebellion in Syria ends.
U.S. officials said that al-Qaida's core leadership group in Pakistan, led by Ayman al-Zawahiri, continues to communicate with affiliates and other followers. But those messages are sporadic and rarely translate into any direct support.
Syria and North Africa have drawn militants from dozens of countries, as well as fighters who have fled regions where al-Qaida has suffered setbacks, including Pakistan and Yemen, U.S. officials said.