For the United States, the goal is to extend to at least a year the period that Iran would need to surreptitiously "break out" toward nuclear weapons development. Daryl Kimball of the Washington-based Arms Control Association said that with the IAEA's additional monitoring, the deal taking shape leaves "more than enough time to detect and disrupt any effort to pursue nuclear weapons in the future."
In exchange, Iran wants relief from sanctions crippling its economy and the U.S. is talking about phasing in such measures.