War has returned to Ethiopia’s Tigray — and former enemies are now fighting together. What changed?

Nearly four years ago, a peace deal ended the brutal war in Ethiopia’s northern Tigray region, one of the deadliest conflicts of the 21st century. Now, the violence has returned — but the battle lines have changed. Tigrayan rebels are again fighting the federal government, while forces that were once enemies are now fighting side by side.

On Wednesday, Tigrayan forces seized three airports controlled by the federal government, while fighting also broke out in the neighboring regions of Amhara and Afar. The hostilities have shattered the 2022 peace agreement that ended a war estimated to have killed around 600,000 people. Relations between the federal government and Tigray’s leaders had been worsening for months.

It’s unclear what led to the recent fighting, with both sides offering conflicting accounts. Tigray’s regional government said federal forces attacked first and that it ordered its forces to respond, calling it a “defensive war.” While Getachew Reda, an adviser to Ethiopian Prime Minister Abiy Ahmed, said the TPLF had launched an “all-out offensive” against government positions in Afar and Amhara and seized the three airports in Tigray, accusing it of taking “irresponsibility to new heights.” The renewed violence this week follows almost two months of smaller clashes. The nongovernmental organization Armed Conflict Location & Event Data Project (ACLED) says fighting between Tigrayan and federal forces began near Ethiopia’s border with Sudan on August 1.

The two sides also accused each other of starting those clashes. According to ACLED, federal drone strikes and Tigrayan troop deployments followed, with Tigrayan forces moving tanks and artillery south this month. National carrier Ethiopian Airlines has suspended all flights to Tigray after the airport seizures.

Tigray People’s Liberation Front (TPLF) fighters prepare for battle at a camp in Mekele, the capital of Tigray region, Ethiopia, on June 30, 2021. It dominated the coalition that governed the country for nearly three decades, despite Tigrayans making up a relatively small share of Ethiopia’s population. That changed after Abiy became prime minister in 2018 following years of anti-government protests.

He introduced political reforms and made peace with neighboring Eritrea, wh…