Despite a track record of misjudgments about weapons of mass destruction, US intelligence officials say they are confident they can verify Iran's compliance with the recently completed nuclear deal.
The main reason, according to a classified joint intelligence assessment presented to Congress, is that the deal requires Iran to provide an unprecedented volume of information about nearly every aspect of its existing nuclear program, which Iran insists is peaceful.
That data will make checking on compliance easier, officials say, because it will shrink Iran's capacity to hide a covert weapons programme.
"We will have far better insight (into) the industrial aspects of the Iranian nuclear program with this deal than what we have today," James Clapper, the director of national intelligence, told an audience last month at the Aspen Security Forum.
Outside experts don't dispute that. But they question - considering past analytical blind spots in the Middle East - whether American spying will really be able to catch every instance of Iranian cheating.
"The intelligence community can rarely guarantee, 'We're going find the secret site,' " said David Albright, a former weapons inspector who heads the Institute for Science and International Security.
"They have found them before in Iran and that's good, but I think they are going to have to do more work and bolster their capabilities to find secret sites in Iran in an environment when Iran is taking counter measures against them."
Skeptics of the deal note that Iran is one of the world's hardest places in which to spy. Iran's intelligence agencies have penetrated CIA front companies, executed Western agents and captured a sophisticated US drone.
The CIA has never had much success developing and keeping good intelligence sources in Iran, says Reuel Marc Gerecht, who worked as a CIA operations officer.
