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 and Mozambique. In 1976 and again in 1988, the Cubans defeated white South African forces in Angola. An estimated 5,000 Cubans were killed in action during the Angolan Civil War. In March 1978, Cuba sent 12,000 regular troops to Ethiopia, assisted by mechanized Soviet battalions, to help defeat a Somali invasion (see Ogaden War). The Cubans and the Russians pushed the Somalis back to their original borders. The presence of a substantial number of blacks and mulattoes in the Cuban forces (40–50 percent in Angola) helped give teeth to Castro's campaign against racism and related prejudice like xenophobia.