Sudan's War and the Horn of Africa Conflict: Alliances that Cross Borders

Sudan's war is no longer confined to the fight between Abdel Fattah al-Burhan's forces and the Rapid Support Forces (RSF), and renewed fighting in Tigray is no longer an internal Ethiopian matter. Tigrayan fighters are present in eastern Sudan, and some of their formations are linked to the front lines there. This places both wars within a wider web of military and political tensions in the Horn of Africa, where internal conflicts intersect with border disputes, armed alliances and competition for influence.

The case of Army 70 is one example of this overlap. The formation, made up of former Tigrayan fighters and officers, is based in eastern Sudan, and some of its members have fought alongside forces loyal to Burhan. Its presence is also tied to the dispute over the Wolkait area in the west of the Ethiopian region. Fighters who crossed into Sudan during Ethiopia's war have therefore become part of a military equation that extends beyond the borders of the country where they took refuge.

This shows how forces that emerged from an internal conflict can become a party to a neighbouring one, and then return to shape the balance of power in their home country. With fighting in Tigray resuming in the second half of 2026, this path is becoming more significant. Armed formations are present on both sides of the border, and the political settlement that was supposed to end the effects of the previous war has stalled.

A peace deal that did not settle the roots of the conflict

The Pretoria Agreement, signed on 2 November 2022, is key to understanding the return of fighting in Tigray. The deal ended the full-scale war between Ethiopia's federal forces and the Tigray People's Liberation Front (TPLF). However, it did not produce a comprehensive political settlement of the issues that triggered the conflict, chief among them the status of disputed territories, the return of displaced people, and security and disarmament arrangements.

In an analysis published by Chatham House on 1 October 2026, titled "War has returned to Tigray. This time it may not stay in Ethiopia", researchers Ahmed Soliman and Abel Abate Demissie argued that the failure to build on the Pretoria Agreement, which ended the war in 2022, stemmed largely from both sides' continued zero-sum approach, along with weak implementation and oversight. They added that the agreement had not delivered the broader political settlement needed for lasting peace.

Wolkait has remained one of the most prominent issues preventing the war from being put to rest. The area is not simply disputed territory. It is bound up with the return of residents displaced during the war, with administrative boundaries and security control, and with the future relationship between Tigray and the Amhara region. Amhara forces have controlled the area since Ethiopia's war, while Tigrayan forces insist it is part of Tigray.

For Army 70, these disputes give its presence in eastern Sudan a dimension beyond its role in Sudan's war. The fighters stationed near the border belong to a military and political environment that sees Wolkait as part of an unresolved cause. The area also lies close enough to link movements inside Tigray with the force's presence on Sudanese soil.

In its report of 18 February 2026, titled "Ethiopia, Eritrea and Tigray: A Powder Keg in the Horn of Africa", the International Crisis Group said the leadership of the Tigray Defence Forces sees the fighters in eastern Sudan, known as Army 70, as a force that could support a military push from the west towards Wolkait. This assessment places the formation within calculations linked to the dispute over the area, alongside its involvement in Sudan's war.

Armed alliances redraw the landscape

The renewed fighting in Tigray coincided with shifts in political and military alliances inside Ethiopia. In September 2026, the TPLF and six other armed groups announced an alliance called the "Survival Alliance", with the aim of removing Prime Minister Abiy Ahmed's government and forming a transitional government.

The alliance includes the Fano movement in the Amhara region and the Oromo Liberation Army, along with four other movements. The announcement came as clashes were spreading in the north of the country. This reflects a shift from a confrontation between the federal government and the TPLF to a landscape in which several armed movements, with different geographical bases and political goals, are intertwined.

In a joint statement, the seven groups said they had formed an alliance called the Ethiopian Peoples' Forces Alliance for Survival, known for short as the Alliance for Survival. They said their goal was to work towards forming an inclusive transitional government. TPLF spokesperson Mikael Asgedom said cooperation between the alliance's members would be political and military, and that joint military operations could become necessary to achieve its goals, according to an Associated Press report published in September.

However, the alliance is not built on a unified political programme or a shared vision for the future of the Ethiopian state. Some of its members fought alongside federal forces against the TPLF in the previous war, and their positions on the disputed territories and on the shape of the political system are at odds. What unites these groups for now is a common enemy, while the historical and political differences between them remain.

The Chatham House report of 1 October addressed these contradictions. It noted that the alliance brings together groups with different visions for Ethiopia's future, that some Fano leaders have declared their opposition to it, and that the Oromo Liberation Army faces internal divisions. The report also said historical differences between the alliance's members could hinder efforts to turn the political agreement into stable military cooperation.

These developments place Army 70 within a wider landscape of armed forces whose operations could overlap with the war in Sudan. The presence of Tigrayan fighters in eastern Sudan, together with armed opposition alliances inside Ethiopia, opens the way for fighters and military expertise to move between battlefields, particularly where border areas are not under the stable control of a single party.

The border becomes a corridor for conflict

The border areas between Sudan and Ethiopia take on added importance because of the terrain and the vast stretches of land where full security control is difficult to impose. In recent years, the corridors between western Tigray and eastern Sudan have seen refugees and fighters move across them, and they have been used as crossing routes by armed groups after the balance of control shifted during Ethiopia's war.

In August 2026, clashes broke out in the Shirerina area of western Tigray, near the Sudanese border. A report published by Mada Masr on 1 October said Army 70 fighters crossed from Sudanese territory into Ethiopia in early August and attacked federal forces' positions near the area. The report said the formation includes thousands of fighters and officers of Tigrayan origin who had served in Ethiopia's armed forces before fleeing or defecting during the war.

Defence analysis group Janes said the clashes on 1 August were the first armed confrontation between the TPLF and federal forces since January 2026. The fighting took place close to the Sudanese border, putting the spotlight back on the role of armed groups based in eastern Sudan.

On 23 September, fighting resumed on a wider scale after Tigrayan forces seized three airports in the region and expanded their operations towards neighbouring areas. The clashes spread to Afar and Amhara, while federal forces and their allies advanced towards Mekelle. As operations continued through October, Sheraro, Rama and central Tigray saw fresh clashes, alongside military movements on fronts close to the border.

This overlap means any escalation in western Tigray could spill over into Sudanese territory, whether through the movement of fighters, the displacement of residents or fighting moving into border areas. The presence of armed formations with past military ties in both countries also adds a new factor to Sudan's war, which has already drawn in fighters from outside the country.

Sudan as a backyard for a regional conflict

The implications of Army 70's presence go beyond its fighters' involvement in Sudan's battles, because the continuing war gives the formation room to maintain its military cohesion outside Ethiopia. At the same time, renewed fighting in Tigray creates the possibility of drawing on this force's experience and geographical position in any move towards the disputed areas.

In an interview with Deutsche Welle, Magnus Taylor, deputy director of the International Crisis Group's Horn of Africa project, said Tigrayan fighters had played an important role in helping Burhan's forces push back the RSF in eastern Sudan and even in Khartoum, and that the relationship had continued since.

This could indicate that the relationship between the Tigrayan fighters and Burhan's forces has gone beyond the presence of foreign individuals on the battlefield to become an ongoing military partnership. According to an analysis published by Horn Review, fighters who previously served within Ethiopia's military establishment offer Burhan's forces a ready pool of experienced infantry, while the fighters maintain an armed presence in Sudan and remain tied to military and political developments inside Tigray.

In its February 2026 report, the International Crisis Group warned that reciprocal military moves were raising the likelihood of a new confrontation, saying shows of defiance by all sides increased the risk of fresh conflict. The warning relates to the presence of armed fighters on both sides of the border, continuing disputes over contested territory, and the stalled implementation of the Pretoria Agreement.

A crisis beyond the reach of local mediation

Efforts to contain the escalation face a fundamental challenge in the number of parties to the conflict and their overlapping interests. Negotiations between the federal government and the TPLF alone are not enough to deal with armed formations outside the region, and disarmament arrangements inside Tigray do not automatically cover fighters who have settled in Sudan and become involved in its war.

On 5 November 2026, a disarmament and rehabilitation programme was launched in Mekelle, targeting about 5,500 former Tigray Defence Forces fighters. However, Army 70, based in eastern Sudan, is not included in the programme, leaving its case separate from demobilisation arrangements inside the region.

Untangling this requires dealing with interconnected issues, including the fate of the disputed areas in western Tigray, the future of armed formations that remained outside the Pretoria Agreement's arrangements, and the presence of Tigrayan fighters in Sudan's war. Handling each issue in isolation leaves room for one conflict to be used to fuel the other.