Fighting has restarted in Ethiopia's Tigray region, and Sudan's civil war is bleeding into it — bad news for civilians across the Horn of Africa.

• Tigray forces tried to retake disputed land in early August and were beaten back, and Ethiopia has since hit the region with repeated drone strikes.
• Eight rebel groups that normally hate each other, including the Tigray TPLF, Amhara Fano militias, and Oromo fighters, have joined an alliance with one goal: removing Prime Minister Abiy Ahmed.
• Sudan's military and Eritrea are backing that alliance because Abiy has been quietly helping their enemy, Sudan's RSF paramilitary — reportedly hosting a training camp for thousands of its fighters.
• The UAE sits behind both relationships, arming the RSF and having earlier rescued Abiy from defeat with a drone airlift.
• The rebel alliance is already cracking, with Oromo fighters clashing with their supposed Fano allies and one prominent Fano figure surrendering to the government.

Outlook: An open war between Ethiopia and Sudan is unlikely since both are stretched thin at home, but the two conflicts are now tangled enough that one mistake could set the region alight.