Not long after this report was prepared, Canadian intelligence learned (from a still-unknown source) that the Argentine government had made arrangements to supply 80-100 tons of yellowcake to Israel. By the end of April 1964, the British had seen the Canadian report. According to a British diplomat, "This means that Israel now has virtually unlimited supplies of uranium free of safeguards." Moreover, if the Israelis had reprocessing facilities, they could produce enough plutonium to "fuel a nuclear bomb" 18-20 months from the beginning of 1964.
The British soon shared the Canadian report with U.S. intelligence, overcoming Canadian reluctance to share it with its neighbors to the south (apparently the Canadians were irritated that the United States would not share the results of a recent American visit to Dimona). The CIA was initially skeptical, but in June 1964, the State Department and the CIA decided that the story should be checked out and sent the query -- reproduced below -- to its embassies in both Argentina and Israel. In September, the U.S. embassy in Buenos Aires confirmed from local sources that during 1963 Israel had arranged to purchase 80 tons of yellowcake from Argentina.
Evidently, the United States took seriously the information it obtained about the Argentine yellowcake sale. Like its British and Canadian allies, Washington was concerned that an Israeli bomb would threaten stability in the Middle East and complicate American efforts to curb nuclear proliferation worldwide. Moreover, to ensure that the Israelis were abiding by their public pledge that the Dimona facility was for "peaceful" use only, Kennedy and Prime Minister Levi Eshkol had secretly agreed in the summer of 1963 to allow American scientists to visit the reactor. The first U.S. team arrived in Dimona in early January 1964, but it is now known that the Israelis made "special arrangements" to prevent the visitors from seeing anything that revealed the true nature of the project.