Here's an interesting story from The Guardian:
'Secret South African documents reveal that Israel offered to sell nuclear warheads to the apartheid regime, providing the first official documentary evidence of the state's possession of nuclear weapons.The "top secret" minutes of meetings between senior officials from the two countries in 1975 show that South Africa's defence minister, PW Botha, asked for the warheads and Shimon Peres, then Israel's defence minister and now its president, responded by offering them "in three sizes". The two men also signed a broad-ranging agreement governing military ties between the two countries that included a clause declaring that "the very existence of this agreement" was to remain secret.
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Israel's nuclear arsenal isn't exactly the world's best kept secret, so these revelations aren't going to have much of an impact in that regard. It will, however, complicate efforts to discredit Judge Goldstone (of the infamous "Goldstone Report" on the Gaza war).