The U.S. has admitted that Saudi Arabia is trying to develop nuclear weapons. In the 1990s, Saudi Arabia purchased CSS-2 ballistic missiles from China. Saudi Arabia has also known to have discussed nuclear weapons development with Pakistan (which has them.) The Saudis have lots of money, and Pakistan needs lots of money. So it doesn't take a rocket scientist to figure out where this might go. The U.S. also has a lot of money, which it has recently been giving to Pakistan. One can assume that there are some "nuclear weapons technology transfer" strings attached. The U.S. is also able to lean on Saudi Arabia somewhat, but if the Saudis are determined to develop nuclear weapons, they could get them.