Despite years of intense surveillance, the U.S. can't find any evidence that Iran is trying to build a nuclear weapon, The New Yorker's Seymour Hersh reports. Hersh argues that we "could be in danger of repeating a mistake similar to the one made with Saddam Hussein's Iraq eight years ago--allowing anxieties about the policies of a tyrannical regime to distort our estimations of the state's military capabilities and intentions." But the White House is pushing back hard against Hersh's claims, with officials anonymously telling Politico's Jennifer Epstein that there's plenty of evidence that Iran is going down a nuclear path.

Hersh offers fascinating details on the techniques the government has used in the last six years to figure out what Iran is up to:

Street signs were surreptitiously removed in heavily populated areas of Tehran--say, near a university suspected of conducting nuclear enrichment--and replaced with similar-looking signs implanted with radiation sensors. American operatives, working undercover, also removed bricks from a building or two in central Tehran that they thought housed nuclear-enrichment activities and replaced them with bricks embedded with radiation-monitoring devices.

High-powered sensors disguised as stones were spread randomly along roadways in a mountainous area where a suspected underground weapon site was under construction. The stones were capable of transmitting electronic data on the weight of the vehicles going in and our of the site; a truck going in light and coming out heavy could be hauling dirt-crucial evidence of excavation work. There is also constant satellite coverage of major suspect areas in Iran, and some American analysts were assigned the difficult task of examining footage int he hope of finding air vents--signs, perhaps, of an underground facility in lightly populated areas.

And yet, there's "no smoking calutron," as one American defense consultant told Hersh--the two most recent National Intelligence Estimates have said there's no conclusive evidence that Iran has tried to make a nuke since 2003. Yet that defense worker, like many Western governments, is still convinced Iran is trying to go nuclear.

Officials in Western Europe and Israel told me what their governments had concluded about Iranian nuclear weapons. Although none knew of any specific evidence of an Iranian weapons program, all said that they believed that Iran was intent on getting the bomb--and quickly. One senior European diplomat complained about America's NIE process. "The American intelligence community was trying desperately not to be blamed anew for an intelligence assessment, as it was in Iraq," he said. "I think Iraq paralyzed the community, and its first NIE on Iran was disastrous, in my view, because it conflated weaponization with the process of developing a nuclear weapon. Weaponization is only a part of the process, but there are other parts as well, including enrichment and the development of delivery systems. Yet to the layman the NIE meant that Iran hadn't been weaponizing. Yes, it may very well be the case that there is no evidence of developing a nuclear weapon. To me, that is not the whole basis of making a judgment. The more important questions are: Is Iran behaving in a way that would be rational if they were not developing a nuclear weapon? And the answer is very clear--their behavior only makes sense if their goal is to have the bomb..."

As a senior administration told Epstein, "[A]ll you need to read to be deeply concerned about Iran's nuclear program is the substantial body of information already in the public domain, including the most recent [International Atomic Energy Agency] report. ... There is a clear, ongoing pattern of deception, and Iran has repeatedly refused to respond to the IAEA's questions about the military dimensions of [its] nuclear program, including those about the covert site at Qom." A senior intelligence official agreed, calling Hersh's article "a slanted book report on a long narrative that's already been told many times over."

The Atlantic's Jeffrey Goldberg writes that clearly those, himself included, who believed Saddam Hussein had weapons of mass destruction should have their thoughts about Iran's nuclear program "constantly tested and red-teamed, to the point of exhaustion." However, the IAEA has just issued a report saying it looks like Iran is trying to build an atomic trigger. Goldberg argues,

The IAEA, of course, is not considered a den of neoconservatives. Nor, for that matter, is the Obama Administration. It's an interesting turn of events: Sy Hersh is accusing an American administration of exaggerating the threat posed by a Middle Eastern adversary, but this time the Administration is led by a man who himself was skeptical about the threat posed by Iraq, and who therefore has some credibility when he asserts, as he has, that Iran is working on a nuclear weapon.