The Ogaden War is a conventional conflict between Somalia and Ethiopia in 1977 and 1978 over the Ogaden region of Ethiopia.

Fighting erupts as Somalia seeks to exploit a temporary shift in the regional balance of power in their favor to occupy the Ogaden region, claimed to be part of Greater Somalia.

In a notable illustration of the nature of Cold War alliances, the Soviet Union switches from supplying aid to Somalia to supporting Ethiopia, which has previously been backed by the United States, prompting the U.S. to start supporting Somalia.

The war ends when Somali forces retreat back across the border and a truce is declared.