High on wins in Tigray, Ethiopia now has Eritrea in its crosshairs

Ethiopia and Eritrea are again facing direct military confrontation around Tigray. Ethiopia says Eritrean troops entered deeply into its territory and claims the right to defend itself under Article 51 of the U.N. Charter. Eritrea calls those accusations a declaration of war and says Ethiopia has planned an invasion for years.

The reported developments include Ethiopian drone strikes near Adirgat on Wednesday and Thursday. An unnamed security source estimated that 5,000 to 8,000 Eritrean troops are deployed in Tigray. Ethiopia’s foreign minister told the Security Council that Eritrean forces had advanced as far as 38 miles into the region.

The crisis is also diplomatic. Ethiopia and Eritrea severed relations on October 1. Ethiopia is battling a renewed rebellion led by the TPLF and allied groups, while Eritrea is accused of backing them. Eritrea has also aligned with Egypt and Sudan’s army, making the confrontation potentially regional.

Tigray is a region in northern Ethiopia. It became the Tigray People’s Liberation Front’s stronghold after Abiy Ahmed became prime minister in 2018. The TPLF is important because it dominated Ethiopia’s politics for nearly three decades before Abiy’s rise, making it one of the country’s most powerful political and military forces.

After Abiy created a new ruling party, the TPLF refused to join it. It also held regional elections despite federal objections. According to Abiy, the TPLF later attacked a federal army base. Those actions helped trigger the first Tigray war in 2020, in which Eritrea fought alongside Ethiopian forces.

The war ended with the 2022 Pretoria agreement, but the TPLF remained central to Ethiopia’s security crisis. In September, it joined six other armed groups in announcing an alliance aimed at removing Abiy and installing a transitional government. Its continued armed position also affects Ethiopia’s border with Eritrea.

The reported Eritrean military presence in Tigray is substantial. An unnamed security source told AFP that between 5,000 and 8,000 Eritrean troops are deployed there. Ethiopia’s foreign minister separately told the U.N. Security Council that Eritrean forces had advanced up to 38 miles into Ethiopia’s northern region.

The reported advance matters because Eritrean troops were supposed to withdraw from Tigray under the Pretoria agreement and its follow-up Nairobi declaration. Those arrangements linked the TPLF’s disarmament to the withdrawal of foreign and non-Ethiopian federal forces. Eritrean troops left larger towns but remained in contested border pockets.

The new movement would deepen that existing presence, according to the article. It also gives Addis Ababa what the article calls a casus belli: a stated reason to fight in self-defense against foreign forces deep inside Ethiopia. Eritrea rejects Ethiopia’s account and calls the accusations a declaration of war.

The 2020–2022 Tigray war ended with the Pretoria agreement, but the settlement left several core security questions unresolved. These included how Tigrayan forces would disarm, who would control disputed territory, and when non-federal forces would leave Tigray. Those gaps allowed mistrust to survive after the ceasefire.

The Nairobi declaration followed the same framework. It tied Tigrayan disarmament to the withdrawal of foreign and non-Ethiopian federal forces. Eritrean troops left the larger towns, but they stayed in contested border pockets. Eritrea was not a party to the Pretoria agreement, and President Isaias Afwerki dismissed questions about its continuing presence as “nonsense.”

The unresolved arrangements now matter because Eritrea’s reported advance appears to deepen its presence in Ethiopia. Ethiopia says it must respond to an incursion, while Eritrea says Ethiopia has long planned to invade. The article presents these competing claims as the basis for renewed military and diplomatic confrontation.

Ethiopia wants access to Assab because it lost access to the sea when Eritrea became independent in 1993. The article describes Assab as an Eritrean Red Sea port and says Prime Minister Abiy has called its loss a mistake “that will be corrected tomorrow.” Access to a port would address a major strategic and economic disadvantage for landlocked Ethiopia.

Ethiopian officials say they seek access through peace and dialogue. Eritrea, however, interprets Ethiopia’s repeated focus on Assab differently. Eritrea’s foreign minister cited a statement attributed to Ethiopia’s deputy chief of staff saying the war’s ultimate objective was to invade Assab. Eritrea used that claim to portray Ethiopia’s policy as an invasion threat.

That disagreement worsens the security dilemma between the neighbors. Ethiopia sees Eritrea’s support for the TPLF and alliances with Egypt and Sudan as encirclement. Eritrea sees Ethiopia’s port ambitions and military strength as grounds to build buffers and coordinate with Ethiopia’s internal opponents.

A wider conflict would matter because Ethiopia and Eritrea are not acting in isolation. Eritrea has opened channels with the TPLF and cultivated Egypt and Sudan’s army as allies. Ethiopia says Eritrea finances and directs rebels, while Eritrea says Ethiopia is preparing to invade. These claims connect the border crisis to Ethiopia’s internal wars and regional disputes.

The mechanism is alliance and counter-alliance. The TPLF, Fano militias, and the Oromo Liberation army announced an alliance seeking to remove Abiy and install a transitional government. Eritrea views the TPLF as a useful buffer, while Addis Ababa sees an armed TPLF, Eritrean backing, and Egyptian and Sudanese alignment as encirclement. Ethiopia and Egypt also expelled each other’s diplomats.

The article does not state a specific consequence if fighting spreads. It does show that more actors could become involved, including armed groups and neighboring states. That would make diplomacy harder and could expand a border confrontation into a broader Horn of Africa security crisis.

Article 51 of the U.N. Charter preserves a state’s inherent right to individual or collective self-defense if an armed attack occurs. It is the legal basis countries commonly cite when claiming they may respond militarily to an attack or incursion. The right exists alongside the U.N. system, rather than replacing the Security Council.

In practice, a country invoking Article 51 is expected to inform the Security Council about the defensive measures it takes. Self-defense is generally understood as requiring a necessary and proportionate response to an armed attack. Whether a particular incident meets that standard depends on the facts and the legal interpretation.

Ethiopia’s foreign minister cited Article 51 after reporting that Eritrean troops had advanced up to 38 miles into Tigray. Eritrea called the accusation a declaration of war. The article does not establish whether Ethiopia’s legal claim satisfies Article 51’s requirements; it records the competing positions.