Answer
The two major external threats faced by Mengistu's government were the Eritrean People's Liberation Front and the Somali invasion. The EPLF was a rebel group that fought for the independence of Eritrea from Ethiopia. The Somali invasion was an attempt by Somalia to annex the Ogaden region of Ethiopia. Both of these threats posed a serious challenge to Mengistu's government and required a significant amount of resources to combat.