What do past nonproliferation failures say about the Iran nuclear agreement?

The history of nonproliferation failures in Israel, India, Pakistan, and North Korea are reviewed in the light of the nuclear agreement with Iran. The paper shows that the circumstances in each case are special and not comparable to the situation in the Iranian case. Thus, while the Iran agreement has some weaknesses, past nonproliferation failures should not be considered predictive of a future failure in this case. But there are lessons to be learned from such failures that should inform U.S. nonproliferation policy generally.