World September 10, 2026 12:05 PM

Two and a Half Decades On: How al Qaeda Has Evolved Since 9/11

From a transnational jihadist network to regional affiliates and rivalries - an account of leadership, expansion and current theatres of activity

By Maya Rios
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Over the 25 years since the attacks of September 11, al Qaeda has shifted from a centralized organisation operating from Afghan sanctuaries to a dispersed network of affiliates and inspired groups across multiple regions. Despite major setbacks - including the death of founder Osama bin Laden and the rise of Islamic State as a rival - the group continues to provide guidance, training and ideological influence to militant actors, particularly in parts of Africa and South Asia. Recent developments, legal proceedings and competing insurgencies have left al Qaeda changed, but still relevant to regional security dynamics.

Two and a Half Decades On: How al Qaeda Has Evolved Since 9/11
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Key Points

  • Al Qaeda originated in the late 1980s under Osama bin Laden and carried out high-profile attacks including the 1998 embassy bombings and the September 11, 2001 attacks which killed nearly 3,000 people - relevant to national security and defence sectors.
  • Since 2001 the group has lost senior leaders - including bin Laden in 2011 and Ayman al-Zawahri in 2022 - but has expanded through affiliates in regions such as Somalia, the Sahel, Iraq, the Arabian Peninsula and Pakistan, affecting regional stability and markets tied to security and investment risk.
  • The rise of Islamic State created a major rivalry that reshaped the jihadist landscape, with ongoing clashes between affiliates of the two groups in places like West Africa; this rivalry influences defence spending and geopolitical risk assessments for energy and trade sectors.

Introduction

Twenty-five years after militants linked to al Qaeda used hijacked passenger jets to strike New York’s World Trade Center towers and the Pentagon, the group has reconfigured itself into a set of regional actors and an ideological reference point for militant violence. The organisation that Osama bin Laden helped establish in the late 1980s has endured leadership losses and strategic setbacks, yet it remains an active influence on violent groups in multiple theatres, most notably across parts of Africa and in South Asia.


Origins and early evolution

Al Qaeda formed in the late 1980s as a transnational jihadist network under bin Laden’s leadership. Bin Laden, a Saudi-born militant with significant personal wealth, had been involved in recruiting and supporting Arab volunteers who fought during the Soviet invasion of Afghanistan after 1979, and he also fought in that conflict himself. The organisation became a focal point for militants seeking to impose hardline Islamist rule and shared a common hostility toward the United States, Israel and governments allied with the United States in the region.

Throughout the 1990s bin Laden’s activities and rhetoric escalated. He lost Saudi citizenship in 1994 and was expelled from Sudan in 1996, after which he took sanctuary in Afghanistan. He began plotting and carrying out attacks on U.S. interests before establishing a public base in Afghanistan. The first strike recognised by U.S. authorities from this period was a 1992 bombing of two hotels in Yemen aimed at U.S. forces that were bound for Somalia; the attack was intended to harm Somalia-bound troops who had already left or were lodged elsewhere.

In Afghanistan he supported training camps and set up an elite brigade of foreign fighters. In 1996 he declared jihad against what he described as U.S. forces occupying Saudi Arabia. A subsequent 1998 announcement created a "World Islamic Front" calling for jihad against "Jews and Crusaders" and stated it was a duty for Muslims to kill Americans and their allies, civilian or military. Later that year al Qaeda carried out truck bombings against U.S. embassies in Kenya and Tanzania, attacks that together killed 224 people.


The September 11 attacks and immediate aftermath

On September 11, 2001, 19 hijackers - 15 of them from Saudi Arabia - commandeered four commercial airliners. Three of the jets struck the World Trade Center towers in New York and the Pentagon near Washington, while the fourth crashed in a Pennsylvania field after passengers stormed the cockpit. Nearly 3,000 people were killed in the attacks.

The U.S.-led military response followed swiftly. In October 2001 the United States invaded Afghanistan, toppling the Taliban regime and dislodging al Qaeda from its established base of operations. Anti-Taliban forces overran al Qaeda positions in the Tora Bora mountains in December 2001. Despite those setbacks, bin Laden evaded capture for a decade, issuing occasional messages until he was killed by U.S. special forces during a raid on his Abbottabad compound in Pakistan in 2011.


Leadership after 9/11

Several other senior figures from the group were captured or killed in the years after 2001. Khalid Sheikh Mohammed, who has publicly described himself as the planner of September 11, was captured in Pakistan in 2003. In 2007 he testified that he planned the operation "from A to Z", according to a transcript released by the Pentagon. A judge recently ordered Mohammed and three co-defendants to face a military tribunal in June 2028, after more than two decades of legal delay; Mohammed remains held at Guantanamo Bay, Cuba.

Bin Laden’s immediate successor, Ayman al-Zawahri, was killed in a U.S. drone strike in Kabul in 2022. Egyptian militant Seif al-Adel is widely believed to be the de facto leader of al Qaeda today.


Geographic spread and violent incidents

As al Qaeda’s leadership scattered, the network’s ideological and organisational imprint persisted through affiliates and inspired actors who carried out deadly attacks across the globe. High-casualty incidents linked to militants associated with al Qaeda or inspired by its doctrine included the 2002 attack on a nightclub district in Bali that killed 202 people; the 2004 train bombings in Madrid that killed more than 190 people; and suicide bombings in 2005 that killed 52 people on London underground trains and a bus.

Branches and affiliated organisations proliferated across regions. In Iraq al Qaeda established a presence and fought U.S.-led forces following the 2003 invasion. A North African branch appeared in 2007, and an affiliate in the Arabian Peninsula was identified in 2009. After 2011, the Nusra Front emerged as a significant player in Syria’s civil war. In Africa prominent al Qaeda-aligned groups include Al Shabaab in Somalia and Jama'at Nusrat al-Islam wal-Muslimin (JNIM) in the Sahel. The group also has ties to Tehrik-e Taliban Pakistan, commonly referred to as the Pakistani Taliban, which has been waging an insurgency against Islamabad.

Analysts note that although the invasion of Afghanistan in 2001 disrupted al Qaeda, the organisation also expanded its footprint in the years that followed. According to one analyst, its profile rose and its influence broadly expanded, peaking around 2013 before a major split with its Iraq-based branch.


The rise of Islamic State and intra-jihadist rivalry

The emergence of Islamic State altered jihadist dynamics in a fundamental way. Abu Bakr al-Baghdadi split from al Qaeda and in 2014 declared a caliphate across substantial territory in Syria and Iraq, leading to clashes with al Qaeda’s Nusra Front and sparking a bitter rivalry. Islamic State was ultimately ousted from its territorial holdings in Syria and Iraq, but the rivalry persists - particularly in West Africa where affiliates of the two organisations frequently clash as they contest territory and influence.

Another turning point occurred in 2016 when the Nusra Front broke away. According to available accounts, its leader Ahmed al-Sharaa, then known by the nom de guerre Abu Mohammed al-Golani, later toppled Bashar al-Assad in 2024, became Syrian president, and reoriented Damascus toward Western partnership. The split and subsequent developments illustrate how fracturing within jihadist movements has produced divergent paths and shifting local dynamics.


Where al Qaeda is most active today

Contemporary al Qaeda activity is concentrated in parts of Africa and South Asia. In Africa, Somalia and the Sahel in West Africa are identified as principal theatres where al Qaeda-aligned groups have been extending control and influence, in some cases governing stretches of territory. In Pakistan, the Tehrik-e Taliban Pakistan has expanded its insurgency in the northwest and has received ideological guidance, training and other forms of support from al Qaeda, according to a recent U.N. report.

Pakistan asserts that much of the TTP leadership and many fighters are based in Afghanistan, where the Taliban returned to power in 2021 after U.S. forces withdrew. A U.N. report released in February noted that al Qaeda continued to enjoy patronage from the de facto authorities in Afghanistan and that its appetite for external operations remained undiminished. Kabul has denied that al Qaeda operates on Afghan soil or that it permits militant attacks on Pakistan from Afghan territory.

One analyst has observed that although al Qaeda has passed the zenith of its influence, it remains remarkably influential. The organisation’s structure has evolved away from reliance on a few high-profile individuals toward a distributed cadre of lower-profile operatives who are harder to identify and target, complicating counterterrorism efforts.


Summary of current posture

Al Qaeda today is less a single hierarchical organisation anchored in one territory and more a constellation of affiliated groups, sympathetic networks and local movements that draw on its ideology. It has suffered the loss of key leaders and the defection of parts of its network, yet it continues to project influence, provide support and inspire violence across multiple regions. The rivalry with Islamic State and the changing landscape in places such as Syria, Afghanistan, Somalia and the Sahel have reshaped how jihadist violence is organised and contested.


Conclusion

Two and a half decades after the attacks that brought the group global infamy, al Qaeda remains a persistent element in the spectrum of transnational militancy. Its shifting structure, regional proliferation and ongoing alliances and rivalries mean it continues to be relevant to regional security dynamics and counterterrorism strategies, even as its character has changed significantly from the organisation that once operated openly from Afghan sanctuaries.

Risks

  • The continued patronage or tolerance of al Qaeda by de facto authorities in Afghanistan, as noted in a U.N. report, raises uncertainty about the group’s ability to plan or support external operations - a security risk for neighbouring states and international stakeholders.
  • The competition and periodic clashes between al Qaeda-affiliated groups and Islamic State affiliates, particularly in West Africa, create unpredictable insurgent dynamics that increase regional instability and can deter investment in affected markets.
  • The organisation’s evolution toward lower-profile operatives and decentralized networks makes detection and targeting more difficult, complicating counterterrorism operations and sustaining a prolonged security threat to defence and intelligence sectors.

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