"The whole non-proliferation regime was based on keeping countries that had bombs from sharing the secrets with countries that didn't -- because that would lower the cost barrier so much that everyone would want one just out of prestige. It largely worked except for Israel (who was given/allowed to steal secrets by France) and South Africa."
The U.S. also played a big part in Israel's getting the bomb. Beautifully documented in "Dangerous Liasons" Patrick & Leslie Cockburn...as I keep saying, great, great book.
Joanna