... At the core of the letter are what Mr. Einhorn, now at the Brookings Institution, called “required elements that have not yet been achieved.” He said that all the signatories supported a negotiated settlement, and “there is no poison pill here” intended to undercut the chance of an agreement.
The letter gets to the heart of some of those areas, all of which are still under negotiation, and in some cases bitter dispute.
For example, the negotiations that ended in April resulted in vague statements about how inspections would work, beyond an understanding that Iran would sign an International Atomic Energy Agency convention that gives inspectors broad rights to investigate suspicious sites. But Ayatollah Khamenei, along with his commanders, immediately ruled out allowing foreigners to visit military sites.
The letter, referring to Iran’s Islamic Revolutionary Guards Corps, said inspections “must include military (including IRGC) and other sensitive facilities. Iran must not be able to deny or delay timely access to any site anywhere in the country.”
Similarly, while Mr. Kerry said last week that it was not necessary to make Iran account for evidence of past effort to work on weapons designs, because the United States and its allies already had “absolute knowledge” of those activities, the former advisers view the long-sought answers to those questions as vital.
The inspectors, they write, must be able “to take samples, to interview scientists and government officials, to inspect sites, and to review and copy documents as required for their investigation of Iran’s past and any ongoing nuclear weaponization activities.” The letter adds, “This work needs to be accomplished before any significant sanctions relief.”
On another delicate issue in the talks, the letter calls for “strict limits on advanced centrifuge R&D, testing, and deployment in the first 10 years,” and for measures to prevent “rapid technical upgrade” when those limits expire. Some limits were negotiated in April, but the details remain to be resolved.
Perhaps the hardest part from an Iranian perspective is the insistence in the letter that the United States publicly declare — with congressional assent — that even after the expiration of the agreement Iran will not be permitted to possess enough nuclear fuel to make a single weapon. ...