Choosing Sides: Tigray’s Return to War and the Horn’s Hardening Blocs

Nexa Insight · Regional Analysis · Horn of Africa Weekly Update — Issue No. 2

Reference: NRTC/HAWU/2026-02  |  Coverage period: 11–22 August 2026  |  Published: 22 August 2026

If last week’s briefing confirmed that no Horn of Africa crisis is contained within its own borders, this week confirmed something sharper: the region’s rivalries are consolidating into two increasingly explicit, named blocs, and the most active front has shifted from the Ethiopia–Eritrea border in the abstract to the Tigray highlands in practice. Eritrean forces have moved into Ethiopian territory, a coalition that has adopted its own name has deployed armour into Tigray, a drone campaign has for the first time this year reached Sudan’s own capital, and a United Nations body has, for the first time, warned in formal terms that South Sudan’s December election risks proceeding without the safeguards meant to make it credible. This briefing sets out what changed this week and why it matters.

1. Ethiopia–Eritrea–Tigray: From Rivalry to Battlefield

The Ethiopia–Eritrea rivalry over Red Sea access, which last week’s briefing described as hardening but not yet militarised on a specific front, has this week acquired one. On 3 August, senior Eritrean military personnel crossed into Ethiopian territory at the border town of Zalambesa, reportedly displaying Eritrean flags; three days later, a coalition operating under the name “Tsimdo” — combining the Tigray People’s Liberation Front (TPLF) with Eritrean government forces — moved tanks and heavy weaponry into the Tigray region. A subsequent drone strike hit Mekelle, Tigray’s largest city, marking what regional analysts describe as a major escalation beyond the low-level clashes that had persisted since the fragile 2022 Pretoria peace began fraying in 2025 (Soufan Center, 2026).

What makes this week’s developments significant is not only the military movement but the alignment it has made explicit. According to the same analysis, the Tsimdo coalition is now backed, in varying forms, by Eritrea, Egypt and Saudi Arabia, alongside Somalia’s federal government and — notably — Sudan’s own army, while Ethiopia’s federal government (ENDF) draws support from the United Arab Emirates and, in an alignment with direct implications for the Sudan war, the Rapid Support Forces (Soufan Center, 2026). A configuration in which Sudan’s army and the paramilitary force fighting it find themselves backing opposite sides of a second, adjacent war is exactly the kind of cross-conflict entanglement this briefing has flagged as the defining feature of the Horn’s current moment.

The near-term risk is not a conventional Ethiopia–Eritrea war fought across their shared border, but continued proxy escalation through Tigray, where the security provisions of the Pretoria Agreement were never fully implemented and where an armed incursion attributed to TPLF-aligned elements was already repelled by Ethiopian forces on 1 August. A second front opening here, layered onto an already contested Red Sea dispute, narrows the space for the kind of confidence-building measures that might otherwise de-escalate either dispute in isolation.

2. Sudan: The War Reaches the Capital

Sudan’s war has, for most of this year, been fought along static front lines in Darfur, Kordofan and Blue Nile. This week’s escalation was different in character: on 12 and 13 August, more than thirty-five drones — attributed by a Sudanese military source to the RSF — struck Khartoum, Omdurman, El Obeid, Kadugli, Atbara and Al-Damar in a coordinated multi-city campaign, the first wave of its kind to reach the capital since May. Sudanese air defences reported downing the majority of the drones, and eyewitnesses in Omdurman described explosions and smoke columns as anti-aircraft systems engaged what one source called a “swarm” (The EastAfrican, 2026a; Sudan Tribune, 2026).

The timing is analytically significant. It follows a period in which the RSF had been losing ground in the west — Sudanese Armed Forces (SAF) and allied Joint Force units have continued to hold the Bir Saliba area near el-Geneina and disrupt RSF supply routes toward Chad — and suggests a paramilitary force compensating for territorial losses with strikes against strategic depth rather than the front line. For civilians in cities that had, until this month, been largely insulated from direct attack, that shift carries its own humanitarian implications, independent of how the ground war in Darfur ultimately resolves.

3. Somalia: Mohamud Moves to End the AU Mission

Speaking in Galmudug on 17 August, President Hassan Sheikh Mohamud called for African Union peacekeepers to leave Somalia outright, telling regional counterparts: “We have reached a point where we can now take full charge of our security. Let’s give African peacekeepers a bunch of flowers and send them home” (AllAfrica, 2026). The statement came in the same week that an extraordinary summit of AUSSOM troop-contributing countries was convening to address the mission’s future (Garowe Online, 2026).

The political confidence behind that statement sits uneasily against the mission’s financial reality. The United States has confirmed it will end its support to the UN Support Office in Somalia (UNSOS) beyond 31 December 2026; UNSOS itself is already operating on a reduced 2026/27 budget of roughly $481.7 million, a 7.5 percent cut from the prior year, and AUSSOM carries an unresolved legacy debt inherited from its ATMIS predecessor (The EastAfrican, 2026b). A president declaring Somalia ready to assume full responsibility for its own security, in the same week his mission’s primary funder confirms its exit timeline, is a statement of political intent that has not yet been matched by demonstrated capability — a gap this briefing has previously identified as a known precursor to insurgent gains when it coincides with contested political legitimacy.

4. South Sudan: The UN Warns the Election Itself Is at Risk

On 21 August, the UN Commission on Human Rights in South Sudan issued its starkest warning yet on the credibility of the country’s planned December 2026 election — the first since independence. Commissioner Barney Afako put it directly: “The guns are returning while the safeguards for peaceful political competition are disappearing” (Jurist, 2026). The Commission noted that none of the six implementation benchmarks set out in the 2018 Revitalised Peace Agreement (RARCSS) have been achieved, and that a bill signed by President Salva Kiir in July formally removed several of the agreement’s pre-election safeguards.

This is a formal escalation of a trend this briefing described last week as the power-sharing arrangement’s “quiet collapse”: what was previously a de facto reality — First Vice President Riek Machar detained since March, fighting continuing in Jonglei State — is now a matter of explicit UN concern that the vote itself, rather than the peace agreement in the abstract, risks lacking legitimacy. An election proceeding on schedule without SPLM-IO’s meaningful participation, against this backdrop, is likely to be contested regardless of its formal legal compliance.

5. Regional Alignments: The Tigray Front Hardens the Blocs

Last week’s briefing flagged an emerging Cairo–Asmara–Mogadishu axis oriented against Ethiopian regional ambitions, and an isolated Addis Ababa. This week’s events sharpen that picture considerably: rather than a loose alignment of shared grievance, the Tsimdo coalition gives that bloc a named, war-fighting structure, while the reported presence of RSF-aligned backing on the Ethiopian federal government’s side pulls Sudan’s own civil war directly into the same alignment structure (Soufan Center, 2026).

For IGAD and the African Union, this is the more consequential development than any single flashpoint: a mediator addressing the Ethiopia–Eritrea dispute, the Sudan war, or the Tigray front in isolation is now, in practice, addressing one interconnected coalition structure with stakes in all three. Multilateral engagement calibrated to bilateral disputes is increasingly overtaken by a regional bloc dynamic that neither IGAD nor the AU has yet organised itself to address directly.

6. Maritime Corridor: The Red Sea’s First Deaths of This Phase

On 11 August, the Houthis struck the Egyptian-owned cargo vessel Tihamah in the Bab al-Mandeb strait with three ballistic missiles in a double-tap attack, killing six people — including three Pakistani nationals and one Indonesian national among the crew, plus two personnel in a secondary strike on the rescue operation — and wounding ten more. Yemen’s Transport Ministry attributed the attack to the Houthis; the group’s own news agency claimed instead to have targeted an unnamed “Saudi ship carrying military equipment.” It is the first shipping fatality linked to the group since the United States and Israel opened their war on Iran on 28 February (Al Jazeera, 2026).

Last week’s briefing characterised Red Sea shipping risk as elevated but not yet resumed at 2024 intensity. This attack does not on its own reverse that assessment, but it ends the run of months without shipping casualties and is a concrete reminder, for Horn of Africa states whose ports at Djibouti, Berbera and Port Sudan depend on sustained confidence in the corridor, that the underlying risk has not been resolved by its recent quiet.

About the Author

Abdinasir Hassan Timoweyne is Chairperson of the Nexa Research and Training Centre and a political analyst specialising in the Horn of Africa and the Middle East. He lectures in International Relations at New Generation University.

References

1. AllAfrica (2026). Somalia: Somali President Tells AU Peacekeepers to Leave. allafrica.com
2. Al Jazeera (2026). Six killed in Houthi attack on Bab al-Mandeb ship, Yemen’s government says. aljazeera.com
3. Garowe Online (2026). Somalia’s Security Future in Focus as Hassan Sheikh Meets Museveni Before AUSSOM Summit. garoweonline.com
4. Jurist (2026). Renewed violence arises in South Sudan as elections near, UN reports. jurist.org
5. Soufan Center (2026). Renewed Tensions Between Ethiopia and Tigray Threaten to Draw in the Wider Region. thesoufancenter.org
6. Sudan Tribune (2026). Sudanese Army Repels RSF Drone Attacks on Khartoum for Second Day. sudantribune.com
7. The EastAfrican (2026a). US funding exit casts doubt on AU peace mission in Somalia. theeastafrican.co.ke
8. The EastAfrican (2026b). Drone attacks target Khartoum, other Sudanese cities amid escalating fighting. theeastafrican.co.ke