Fighting erupted again in Ethiopia's Tigray region on September 23, with Tigrayan forces launching a major offensive that has spread into the neighboring Afar and Amhara regions. The escalation directly threatens the 2022 Pretoria peace agreement that ended a war which killed an estimated 600,000 people. The TPLF has now joined six other Ethiopian armed groups — including the Amhara Fano movement, its former battlefield enemy — in an alliance seeking to remove Prime Minister Abiy Ahmed's government. The geography matters as much as the politics. Fighting in Afar threatens Ethiopia's main trade corridor to Djibouti, the lifeline for a landlocked nation. Beyond Afar sits Eritrea, whose troops fought alongside Ethiopian federal forces during the 2020-2022 war but whose relations with Addis Ababa have since deteriorated sharply. Ethiopia's push for Red Sea access has deepened Eritrean security anxieties. Martin Plaut, a Horn of Africa expert, told DW that Eritrea could become directly involved, and that such a conflict could then draw in Sudanese forces. The proxy architecture is already in place. Ethiopia is alleged to host a base in its west supplying and training RSF fighters in Sudan's civil war — a claim DW has not independently verified. Eritrea, Egypt, and Saudi Arabia are identified as backing the opposing Sudanese Armed Forces. The UAE faces allegations of supporting the RSF, which it denies. Jalale Getachew Birru of ACLED stressed that Ethiopia's conflict is not isolated: it involves neighboring countries and is being displayed across the Horn. The African Union responded on September 23 with a statement from Commission Chairperson Mahmoud Ali Youssouf warning that new political and military alliances risk reversing progress made since 2020. The AU called for an immediate ceasefire, renewed direct talks under the Pretoria framework, and restraint by Ethiopia's neighbors. Former Nigerian President Olusegun Obasanjo was tasked with supporting diplomatic efforts as the AU's high representative for the Horn. The Red Sea dimension adds a layer of global consequence. The Bab el-Mandeb Strait, flanked by Eritrea and Djibouti on one side and Yemen on the other, is one of the world's most critical shipping chokepoints. Eritrea's control of the port of Assab gives it strategic significance well beyond the Tigray theater. Any serious deterioration of Ethiopia-Eritrea relations could affect the security architecture of the entire Red Sea corridor, where Saudi and Emirati interests overlap in some areas and diverge sharply in others — particularly over Sudan. None of this makes a single unified regional war inevitable. The seven-group Ethiopian opposition alliance is not a unified military force; its members have competing political objectives and territorial interests. Eritrea may calculate that direct intervention is too costly. Sudan's warring parties have their own priorities. But as Plaut warned, these conflicts do not need a common command structure to become interconnected. The mechanism is chain reaction, not conspiracy: each bilateral escalation creates incentives for actors in adjacent conflicts to exploit the new situation. The humanitarian stakes are concrete. The previous Tigray war killed an estimated 600,000 and displaced millions. The Pretoria agreement stopped large-scale fighting but left the underlying political and territorial disputes unresolved. Today, Ethiopia faces armed movements on multiple fronts, Eritrea is a potential military actor, Sudan is engulfed in civil war, and Gulf powers are backing opposing sides across the region. The question is not whether all these threads will merge into a single war — it is whether enough of them will intersect to produce a catastrophe larger than any individual conflict.
