“As a fuel for weapons, plutonium packs a far greater punch than uranium, and in bulk can be easier and cheaper to produce,” writes The New York Times , “Which is why some nuclear experts voice incomprehension at what they see as a lopsided focus on uranium in evaluations of the deal reached with Iran — under which Tehran would forsake the production of plutonium.”  

“Atomic experts call the uranium focus potentially misleading, because it is the lesser path to the bomb. In secret, three decades ago, Iran began exploring the plutonium path and was perhaps only months from inaugurating a plant for its production when, last year, as negotiations gained momentum, it abruptly agreed to a fundamental redesign that would end the facility’s potential for making substantial amounts of bomb fuel.”  

“Why did Iran give up plutonium? Dr. Hecker, the former director of Los Alamos, said Tehran had probably decided to abandon its push for an arsenal. But he argued that the nation’s hard bargaining to save much of its uranium complex suggested that it still wanted to hedge its bets.”