A rebel victory in Ethiopia’s Tigray region risks triggering more conflict elsewhere in the country, placing both Prime Minister Abiy Ahmed’s political future and his economic reform plans in peril. On June 30, Abiy said Ethiopian forces had withdrawn from Tigray’s regional capital of Mekelle because it was no longer the “center of gravity for conflicts.” The prime minister’s public remarks were his first since the Tigray People’s Liberation Front (TPLF) announced they took control of Mekelle on June 28 after launching an offensive two weeks before that forced Ethiopian troops to flee the city. A senior Western official told The Wall Street Journal that the TPLF offensive destroyed a “sizable number” of the Ethiopian National Defense Force (ENDF) divisions deployed to Tigray and took “thousands” prisoners of war, lending credence to the TPLF’s claim that a major military operation forced their exit and that it was not just a...