...Iran and the major powers missed Tuesday's deadline for a final deal and have given themselves until July 7 to reach one.
Some of the toughest issues that remain are the pace of sanctions relief and the monitoring and verification steps that major powers want to ensure Iran does not cheat on any accord.
In a sign of verification's importance, the International Atomic Energy Agency U.N. nuclear watchdog said its head, Yukiya Amano, was going to Tehran to discuss the issue, as well as the past potential military dimensions (PMD) of Iran's program.
U.S. officials say they want to remedy a key weakness in the international nonproliferation regime that allows a country to drag out negotiations with the IAEA indefinitely for access to suspect sites.
Without timely access, including, if necessary to military sites - which Iran's supreme leader said is a red line that he will not cross - finding out if a state is hiding a nuclear program becomes a markedly harder challenge.
"I fail to see how any agreement can pass muster ... that doesn’t have snap inspections (at all sites)," former U.S. deputy secretary of State Richard Armitage told Reuters. "I don’t see how you can have a verifiable regime without having snap inspections - whenever, wherever."...