Magnus Malan, a South African general and defense minister who in the 1980s helped devise and carry out his nation’s last-ditch strategy to preserve its system of rigid racial segregation, including ordering raids into surrounding countries, died on Monday in Cape Town. He was 81.

A family spokesman said the cause was heart failure, The South African Press Association reported.

General Malan used the phrase “total onslaught” to describe the threats to apartheid, as the country’s racial laws were known. He saw those threats coming from Communists, neighboring African countries and liberals in the United States. His answer was “a total strategy,” combining elements of the political, economic and psychological spheres as well as the military.

He approved counterinsurgencies in Mozambique and Angola; set up a covert agency responsible for disinformation and assassination; sent troops to control unrest in so-called townships, areas designated for blacks; and declared that political rights were not a relevant concern for blacks. He and his aides regularly used terms like “annihilate” and “exterminate.” He approved a biological warfare program....