The South African Border War was closely linked to the Angolan Civil War. South African expeditionary units had openly invaded Angola in 1975 during "Operation Savannah", an ill-fated attempt to support two rival Angolan factions, the National Union for the Total Independence of Angola (UNITA) and the National Liberation Front of Angola (FNLA), during the civil war. The SADF was forced to withdraw under overwhelming pressure from thousands of Cuban combat troops. When South Africa began intensifying its campaign against PLAN in the 1980s, it reasserted its alliance with UNITA and took the opportunity to bolster that movement with training and captured PLAN weaponry.