Twenty-five years after 9/11 recast the Horn of Africa as a front line in a global campaign, the honest verdict is neither victory nor defeat. The counterterrorism effort has prevented state collapse in Somalia, suppressed piracy, and stopped mass-casualty attacks in regional capitals. It has not defeated Al-Shabaab, which in 2025 launched its most serious offensive in years, and the Global Terrorism Index now identifies sub-Saharan Africa as the epicentre of global terrorism. The strategy has bought time and denied the enemy victory without producing a durable peace. Part of the reason is that the adversary has evolved: Al-Shabaab exemplifies fifth-generation terrorism, functioning simultaneously as an ideological movement, an economic enterprise and a proto-government.
The US-led post-9/11 counter terrorism architecture in the Horn of Africa was assembled quickly and expanded steadily. The Combined Joint Task Force-Horn of Africa was established in October 2002 and moved to Camp Lemonnier in Djibouti in May 2003, becoming the only permanent US military base in Africa. Washington layered civilian and military programmes on top: the East Africa Counterterrorism Initiative from 2003, later succeeded by the Partnership for Regional East Africa Counterterrorism from 2009, and the creation of AFRICOM in 2007, which assumed responsibility for CJTF-HOA in October 2008.
Over time the model shifted from large deployments toward training local surrogate forces under US budgetary authorities such as Section 127e and Section 333. The clearest product is Somalia’s Danab (“Lightning”) Brigade, formed in 2014 with US funding channelled through the contractor Bancroft Global Development, which the Center for International Policy records as having grown from a pilot platoon to around 3,000 to 4,000 personnel. Kenya developed comparable units, including a Ranger Strike Force and the General Service Unit’s Recce Company, both of which featured in the response to major attacks.
The multilateral pillar was the African Union’s mission. AMISOM deployed in March 2007 with 1,650 Ugandan and Burundian troops and grew to more than 22,000 at its 2014 peak, before transitioning to ATMIS in April 2022 and then to the African Union Support and Stabilization Mission in Somalia (AUSSOM) in January 2025. The European Union has been the single largest direct contributor, providing nearly €2.7 billion to the AU missions in Somalia since 2007.
What the data shows
The global trend data tells a story of displacement of violent extremism into new theatres rather than defeat. As such, Sub-Saharan Africa has emerged as the most active theatre of violent extremism, recording the most terrorism deaths of any region for eight consecutive years, and the Global Terrorism Index 2025 ranked Somalia seventh worst in the world, with a score of 7.614. Somalia’s fatalities reached a record high in 2023 before falling in 2024, according to ACLED-based analysis by the Africa Center for Strategic Studies, which recorded a 41 per cent drop that still left 2024 deaths well above 2020 levels.
Similarly, the main terrorist group in the Horn of Africa, Al-Shabaab, has proved extraordinarily resilient. The UN Monitoring Group estimate, still cited by the US Congressional Research Service, put its fighter strength at between 7,000 and 12,000, larger than a decade earlier despite sustained losses. Lower figures of 3,000 to 7,000 that still circulate date from earlier assessments, while the Somali government has claimed as many as 18,000. The UN Monitoring Team’s latest report (S/2026/651), released on 10 August 2026, cautions that reliable data on fighter numbers are difficult to obtain, but describes a group adapting rather than retreating. Senior commanders have been killed and its revenue from Mogadishu has fallen from an estimated $12–15 million to $5–9 million a month, yet the group has shifted to more targeted, strategic attacks, is seeking longer-range artillery and drone-jamming technology, and may have had between 150 and 400 fighters trained by the Houthis. The group’s finances explain much of this durability: UN monitors estimated its revenue rose from $100 million to $150 million between 2021 and 2022 through taxation, extortion and port levies, a sum comparable to the federal government’s own domestic revenue. Self-financing frees the group from external patrons and lets it tax areas it does not hold, turning a fighting force into a rival authority.
While US kinetic pressure in the region reached unprecedented levels in 2025, with AFRICOM confirming 101 airstrikes in Somalia compared to just 10 in all of 2024, Al-Shabaab launched its Shabelle offensive, recapturing towns in Middle and Lower Shabelle, including the strategic hub of Adan Yabaal. The group also advanced to within about 50 kilometres of Mogadishu.
A second threat has grown in the north of Somalia; the Islamic State in Somalia (ISS), based in Puntland’s Cal Miskaad mountains, runs the al-Karrar office, a financial hub that channels money to IS branches across Africa. AFRICOM estimates the faction grew from about 300 fighters in 2019 to around 1,500 by May 2025, roughly 60 per cent of them foreign. Puntland’s Operation Hilaac, launched in late November 2024, retook territory, and in July 2025 a rare US ground raid captured the group’s finance chief.
Where the strategy failed or backfired
The most consequential failure predates the current campaign. Ethiopia’s US-backed intervention in December 2006, which routed the Islamic Courts Union, is widely assessed to have radicalised and popularised Al-Shabaab, transforming a marginal youth militia into a nationalist insurgency. The intervention illustrates a recurring pattern: heavy-handed foreign military action generating the grievances that sustain the movement it targets.
Kenya’s experience shows the same dynamic domestically. Following Operation Linda Nchi in which Kenya sent troops into Somalia in 2011 to counter increased security threats , Al-Shabaab responded with attacks on Kenyan soil: Westgate mall in 2013 (67 killed), Garissa University in 2015 (148 killed), the DusitD2 complex in 2019 (21 killed), and the Manda Bay base in 2020 (three Americans killed). Kenyan forces also suffered catastrophic losses in Somalia at El Adde in 2016.
Kenya’s domestic response led to complaints by local communities, citing government’s overreach. This contributed radicalisation and increased extremism. Ensuing grievances became recruitment material, as Al-Shabaab fused local exclusion with its global jihadist narrative. Further, Somalia’s droughts exposed the securitisation of aid. Al-Shabaab’s blockades and aid denial during the 2020-2023 drought worsened conditions, though this backfired and helped trigger the clan uprising that fuelled the 2022 government offensive.
What worked
Set against that record of failure is a narrower record of achievement, easy to overlook because it consists largely of disasters that did not happen. Piracy is the clearest case. Somali hijackings in the Gulf of Aden, which peaked in 2011with 237 attacks, paralysed one of the world’s busiest shipping lanes. Concerted naval patrolling by combined international task forces, together with hardened merchant shipping practice, suppressed the trade almost to zero within three years, though a modest resurgence has appeared since 2024. Mass-casualty attacks in regional capitals have also become rarer, and where they have occurred the response has been markedly faster. Nairobi has seen no atrocity on the scale of Westgate or Garissa since the DusitD2 attack in 2019, when police and specialist units cleared the complex within hours rather than the days it took at Westgate — a direct dividend of the rapid-response capacity built after 2013. The survival of the Somali federal government, the recovery of Mogadishu from Al-Shabaab control in 2011, and the steady attrition of the group’s senior leadership through strikes and raids all count as real achievements. Somalia in 2025 is a weak state under sustained pressure; without the intervention of the past two decades it might well have been no state at all.
Diplomacy has occasionally achieved what force could not. In January 2024 Ethiopia signed a memorandum of understanding with Somaliland, trading the prospect of recognition for access to a stretch of coastline, and Mogadishu read it as an assault on its sovereignty. The rupture over the January 2024 Somaliland MoU, which threatened Ethiopian participation in AUSSOM and with it thousands of troops holding ground in the Somali interior, was defused by the Turkish-mediated Ankara Declaration of December 2024, which restored working relations — an example of regional diplomacy averting a security vacuum that no amount of airpower could have filled.
The spillover and the funding cliff
The threat has not been defeated so much as displaced. As pressure on Al-Shabaab mounted inside Somalia, jihadist violence spread west and south into theatres with weaker states, thinner intelligence coverage and nothing resembling the counterterrorism architecture built around the Horn. In the Great Lakes, the Allied Democratic Forces — a Ugandan insurgency driven into eastern Congo in the 1990s and rebranded in 2019 as Islamic State Central Africa Province — carried out the November 2021 Kampala bombings, and prompted the joint Ugandan-Congolese Operation Shujaa, which has pushed the group deeper into the forests of North Kivu and Ituri without dismantling it. The DRC now ranks among the world’s ten worst-affected countries by terrorism deaths, even as the M23 crisis draws Kinshasa’s troops, attention and regional diplomacy away from the campaign against ISCAP.
The gravest near-term risk, however, is neither Al-Shabaab nor the Islamic State but the budget. AUSSOM took over from ATMIS in January 2025 already underfunded, after the UN Security Council failed in May 2025 to authorise financing under Resolution 2719 — the hybrid mechanism that would have met most of the mission’s costs from assessed UN contributions rather than voluntary donor pledges — because of US opposition. The mission faces a shortfall exceeding $92 million on top of debt inherited from ATMIS, at precisely the moment its adversary is back on the offensive. Simultaneously, the US suspended $125.5 million in aid to Somalia in early 2025 amid USAID restructuring, and announced it would end support for UNSOS logistics by the end of 2026 — the supply, fuel and medical backbone on which AU troops in the field depend. The result is a funding cliff arriving well ahead of any political settlement: capacity is set to fall just as the requirement rises.
Conclusion and policy implications
Twenty-five years of effort have produced neither the collapse of Al-Shabaab nor the collapse of the Somali state. The verdict is costly containment — a holding action sustained by external money and firepower that are now both receding. Three conclusions follow for regional actors. First, the security-first model has reached its limits, and the funding cliff makes a purely military posture unaffordable; troop-contributing countries and the AU should press for a predictable financing mechanism while planning a realistic, slimmer force. Second, the record of the past two decades shows that heavy-handed responses, whether foreign military intervention or coercive domestic policing, have tended to generate the very grievances militants exploit , which argues for governance and grievance-reduction as core security investments, not afterthoughts. Third, Al-Shabaab’s financial resilience means that choking its revenue — the taxation, extortion and port levies that UN monitors valued at $100 million to $150 million — matters as much as airstrikes, as does contesting its shadow governance and its online influence on the cognitive battlefield. The war has been fought to a standstill . Winning it will require the actions that guns cannot deliver.The tools that defeated fourth-generation terrorism will not defeat its fifth generation.
NOTE
The fifth-generation terrorism conceptualization is contained in the forthcoming monograph, “From the Sicarii to the Islamic State: A Five Generation Framework for the Evolution of Terrorism”, authored by Dr Mustafa Y. Ali. A special paper on the same topic was published by this Institute.
