RSA Nuke Test

The Economist opens an article with this line, "With the possible exception of South Africa, no country that has tested an atomic bomb has given its nuclear weapons up."

I thought there was confirmation of South Africa stopping its WMD program. So a brief search took me to this site. Apparently the open question is whether or not RSA conducted a test. They had prepared for a test in 1977 but bowed to international pressure. In 1979 a flash was detected over the Indian Ocean. Experts could not determine the origins of the blast or even if it was nuclear.