According to a detailed account contained in Time magazine, Israel assembled about a dozen bombs and readied them for use during the October 1973 Arab-Israeli war. The bombs could have been delivered by aircraft or missiles. In 1974, Israeli President Ephraim Katzir said that "it has always been our intention to develop a nuclear potential ... We now have that potential." This remark was followed five years later by a spectacular and still controversial event.
On September 22, 1979, an American "Vela" satellite detected a distinctive double flash off the southern coast of Africa. The satellite data, together with other information from U.S. intelligence sources, offered strong evidence that the flash had been caused by a low-yield nuclear explosion. Defense Department and State Department officials pointed out that this was only the 42nd time that a satellite of this type had registered such a signal; and in the first 41 cases, according to these officials, the Vela had correctly detected atmospheric nuclear tests. A State Department official later told the Washington Post: "Look, the Vela satellite picked up a signature like this 41 times before. In every one of those 41 instances, there was never any question about the fact that a nuclear test had taken place. Each of those 41 was undeniably a nuclear explosion. This was, too."
A 1979 CIA memorandum stated that "of all the countries which might have been responsible for the 22 September event, Israel would probably have been the only one for which a clandestine approach would have been virtually its only option." The CIA also observed that Israelis had participated in South African nuclear research during the preceding several years.
In June 1980, the CIA reported to the National Security Council that a 2-3 kiloton nuclear test had taken place at the time and place of the Vela reading, and that it had probably involved Israel and South Africa. However, a panel of scientific experts assembled by the Carter White House analyzed the technical data and concluded that the information was too ambiguous to prove that the event was a nuclear test.