When nuclear monitors said Iran had started testing a single advanced centrifuge last year, some U.S. politicians and analysts jumped on the report as proof the Islamic Republic can't be trusted.
To U.S. officials negotiating with Iran, it was probably just a mistake -- one that shows the pitfalls in the highly technical accord being discussed. Describing the incident in detail for the first time, U.S. officials, who asked not to be identified following diplomatic rules, said the testing was probably done by a low-level employee on Iran's nuclear program who didn't understand the limits placed on his experimentation.
Two weeks later, at a congressional hearing in Washington, politicians and trade analysts used that IAEA report to argue Iran was violating the terms of an interim accord curtailing sensitive nuclear activities in exchange for limited sanctions relief.
"How has the administration responded to this evidence of Iranian cheating?" asked South Carolina Republican Representative Joe Wilson.
"This is an example of what Iran does when I say they cheat incrementally and not egregiously and that they are testing the boundaries of our willingness to respond," said Mark Dubowitz, executive director of the Foundation for Defense of Democracies, a Washington research center that has helped draft sanctions on Iran. "There were no sanctions, there was no economic cost and the message to Iran is: when there is a comprehensive agreement, you can cheat incrementally."