On a warm evening last month, Tariku Debela was walking home from dinner in the immigrant enclave of Eastleigh, Nairobi, when he was jumped by four men who took his phone and more than $200 in cash. Getting mugged is bad enough, but what happened next is seared in Debela's memory.

Debela is an Oromo political leader residing in Kenya as a refugee. The men who robbed Debela delivered a message in Amharic—a verbal threat from across the border—"side with the Ethiopian government or only death awaits you."