If Barack Obama is to persuade Iran to negotiate away its illegal nuclear weapons program, he will first need to generate more leverage than what the Bush administration is leaving him with. The current U.N. sanctions have proven too weak to dissuade Tehran's leaders, and Russia and China seem determined to keep those sanctions weak. Meanwhile, the regime continues to insist there are no incentives in exchange for which it would halt or even limit its nuclear work.

However, Tehran has an economic Achilles' heel -- its extraordinarily...