NAIROBI, Kenya — Fighting has returned to Ethiopia’s Tigray region, where former enemies are joining forces against the government and the peace agreement that ended one of Africa’s deadliest recent wars appears close to collapse.

The crisis could merge conflicts in several parts of Ethiopia and draw neighboring Eritrea into another war. Here are five things to know:

Federal and Tigrayan forces accuse each other of restarting hostilities nearly four years after signing the Pretoria peace agreement.

Ethiopian Airlines suspended flights to Tigray this week following the seizure of Mekelle airport by Tigrayan forces. Residents told The Associated Press that roads connecting Tigray with the neighboring Afar region had been closed, although AP could not independently verify the closures.

Internet monitor NetBlocks also reported disruptions across northern Ethiopia, reviving memories of the previous war, when Tigray was largely isolated and civilians struggled to obtain food, medicine and reliable information.

The Tigray People’s Liberation Front has joined six other opposition groups in an alliance that aims to remove Prime Minister Abiy Ahmed’s government.

Its members include the Amhara Fano National Movement and the Oromo Liberation Army. Tigrayan and Amhara forces fought on opposing sides during the previous war.

Magnus Taylor, deputy project director for the Horn of Africa at the International Crisis Group, described the coalition as combining political opposition to Abiy with an “opportunistic military alliance.”

Effective coordination could force federal troops to fight across several regions. But it remains unclear whether groups divided by territorial disputes and deep grievances can conduct joint military operations.

The Pretoria agreement ended major fighting in November 2022 but left disputes over territory, security and accountability unresolved.

Taylor said the agreement was “on life support.” A TPLF spokesman told the AP this week that it was no longer valid.

Laetitia Bader, a regional director at Human Rights Watch, said key provisions had been violated for years. She cited continuing abuses, including what the organization describes as the forced expulsion of ethnic Tigrayans from western Tigray. AP could not independently verify the allegations.

Eritrean troops fought alongside Ethiopia’s federal forces during the previous Tigray war. Relations between Addis Ababa and Asmara have since deteriorated sharply.

Ethiopia has accused Eritrea of supporting armed opponents. Eritrea has accused Abiy’s government of preparing for war as Ethiopia presses for greater access to the Red Sea.

Taylor warned that the fighting could spread across Ethiopia and draw in Eritrea. That would create another regional conflict next to Sudan, which is already experiencing a devastating war and humanitarian crisis.

Researchers at Ghent University have estimated that the earlier war caused about 500,000 civilian deaths in Tigray alone. The estimate includes deaths from direct violence, but researchers attributed most of the toll to famine and the collapse of the region’s health system. The conflict also displaced millions of people across northern Ethiopia.

The war’s effects persisted after the ceasefire, with researchers later documenting deaths from hunger in Tigray.

Bader warned that another Ethiopian conflict could deepen the wider regional emergency. Transport and communications restrictions could quickly interrupt supplies of food and medicine while making civilian suffering harder to document.

Preventing a wider war would require an immediate halt to the fighting, renewed negotiations and sustained international pressure before Ethiopia’s separate conflicts converge.

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