The renewed clashes in Ethiopia come nearly four years after the Pretoria peace agreement ended the devastating Tigray war.

Now the Tigray People’s Liberation Front (TPLF)and six other opposition groups have formed an alliance opposed to Prime Minister Abiy Ahmed’s government.

So what has brought former enemies together? Why has fighting erupted again? What role could neighboring Eritrea play, and could the conflict spread across the wider Horn of Africa?

Martin Plaut, journalist and Senior Research Fellow at King’s College London's Department of War Studies and author of "Understanding Ethiopia’s Tigray War," speaks to DW.