Obama's critics are real gamblers on Iran

U.S. President Barack Obama speaks during the NAACP's 106th National Convention in Philadelphia, Pennsylvania on July 14, 2015.

(CNN)The crucial reason the sanctions have been so effective — more than critics expected — is that they are comprehensive. Leaky sanctions, especially when the leaks are in major countries such as China, Russia and India, are worthless, perhaps even almost counterproductive. They don't inflict much pain on the regime and actually benefit the hard-liners who control the few gateways in and out of the economy.

There is a profound gap between the United States and the world in the perception of the sanctions against Iran. For many in the United States, the sanctions are a mechanism to punish an evil regime. But for most of the other countries involved, the sanctions were enacted specifically to bring Iran to the negotiating table. These countries would not allow them to be turned into a permanent mechanism to strangle Iran. They all have relations with Iran, traded with it pretty freely until 2012, and intend to resume and expand these ties.