According to declassified British and US documents that the Washington, DC-based research group National Security Archive (NSA) made public on June 25, Israel secretly bought 80-100 tons of Argentine uranium oxide ("yellowcake") in the 1963-1964 period. The uranium ore was purchased to be used as fuel at Israel's Dimona nuclear reactor in the Negev desert and ultimately for producing plutonium for the country's clandestine nuclear weapons program. France had cut off Israel's supply of French uranium, and the Israeli government was looking for new sources, including South Africa and Argentina. The Argentine president at the time was Arturo Umberto Illia (1963-66) of the centrist Radical Civic Union (UCR).
British and US intelligence learned of the purchases from Canadian intelligence in March 1964 and received confirmation from the US embassy in Buenos Aires that September. The UK and the US were concerned that an Israeli nuclear weapons program would have a destabilizing effect on the Middle East. They tried to get information from Israel and to persuade Argentina to apply stronger safeguards to uranium sales, with little success in either effort.
Canada, the UK and the US "routinely acted with the utmost discretion when sharing intelligence information about the Israeli nuclear program," the NSA noted, and "they kept the entire yellowcake sale secret. On this matter there were no leaks; the issue never reached the US media then or later." The US documents on the sales were declassified in the middle 1990s, according to the NSA, but "they lingered in a relatively obscure folder in the State Department's central foreign policy files at the US National Archives. They may never have been displayed in public before, as the file appeared to be previously untouched." (NSA, June 25; La Jornada, Mexico, July 2, from correspondent)
From Weekly News Update on the Americas, July 7.