In November 1975, Cuba poured more than 65,000 troops and 400 Soviet-made tanks into Angola in one of the fastest military mobilizations in history. South Africa developed nuclear weapons due to the threat to its security posed by the presence of large numbers of Cuban troops in Angola. In 1976 and again in 1988 at the Battle of Cuito Cuanavale, the Cubans alongside its MPLA allies defeated UNITA rebels and apartheid South African forces. In March 1978, Cuba sent 12,000 regular troops to Ethiopia, assisted by mechanized Soviet battalions, to help defeat a Somali invasion. Ethiopians backed by Cubans and Soviets pushed the Somalis back to their original borders.