United Nations Security Council Resolution 428, adopted unanimously on May 6, 1978, after hearing representations from the People's Republic of Angola, Zambia and the South West Africa People's Organisation (SWAPO), the Council reminded Member States to refrain from using threats and use of force in their international relations. Reiterating Resolution 387 (1976), the present resolution condemned South Africa for its armed invasion of Angola via South West Africa (Namibia).