In 1963, during a Security Council debate on apartheid, politician Adlai Stevenson announced dramatically that the U.S. had banned all sale of arms to the Republic of South Africa. The step had been taken, he said, to show U.S. government's deep concern that South Africa refused to abandon its racist policies. In March 1963, a reactor went critical at a research center near Pretoria, and South Africa joined the nuclear age. The feat was made possible by the firm that designed and built the equipment: Allis-Chalmers of Milwaukee, Wisconsin.