Iran’s supreme leader on Thursday challenged two of the United States’ bedrock principles in the nuclear negotiations, declaring that all economic sanctions would have to be lifted on the day any final agreement is signed and that military sites would be strictly off limits to foreign inspectors.
If Iran insists on such a position, it would cripple a very important component of verification, as Iran would have carved out a "safe harbor" from which it could engage in prohibited nuclear activities. IMO, if Iran is genuinely serious about the peaceful purpose of its nuclear activities, it should permit inspections that could be conducted anytime and anywhere.
Whether or not Khamenei is posturing remains to be seen. If he's serious about the above position on inspections, the P5+1 should reject any agreement, on account of a lack of verifiability.