A prominent Iranian nuclear scientist has defected to the U.S., aiding American hopes of curtailing Iran's nuclear ambitions, according to ABC News. The scientist, Shahram Amiri, disappeared last year while in Saudi Arabia. In response, Iranian officials accused the U.S. of kidnapping Amiri, but U.S. officials now say he had agreed to American offers to defect. What will his defection mean for the tense U.S.-Iran relationship and for the Iranian nuclear program?

• U.S. Intel Will Rely Heavily on Amiri  The Washington Independent's Spencer Ackerman writes, "Expect a new National Intelligence Estimate on the Iranian nuclear program to rely significantly on Amiri."

• Why It Might Mean Little  High-ranking Clinton- and Bush-era counterterrorism official Richard Clarke downplays the impact of recruiting Amiri, whose knowledge probably only includes a small part of the Iranian nuclear program. "The significance of the coup will depend on how much the scientist knew in the compartmentalized Iranian nuclear program ... Just taking one scientist out of the program will not really disrupt it."

• Proves There Is No Iranian Nuclear Program Middle East blogger Juan Cole notes, "US intelligence continues to maintain that Iran has not committed to having a nuclear weapons program. Presumably this information came from Amiri and is fresh and solid, since he is a consummate insider ... Iran does not have a nuclear weapons program at the moment. It can't move closer to nukes if it doesn't have a weapons program!"

• The French Connection?  Foreign Policy's Blake Hounshell notes that the U.K. Telegraph reported Amiri's defection back in December, but credited French intelligence, not the CIA. Meanwhile, the new ABC News story does not cite specific sources, but Hounshell has a good guess. "FYI: It so happens that a French delegation is in town for President Nicolas Sarkozy's visit," he notes. Could French intelligence be behind the defection? Or are they just leaking the story to the press?

• Our Most Successful Weapon Against Iran  Surveying the recent spate of defections and similar incidents, The Guardian's Julian Borger declares: "It is clear that there is a concerted intelligence effort underway aimed at the Iranian nuclear programme, and that it has been the most successful element of western policy in recent years, as waves of sanctions and military threats have failed to divert Tehran's ambitions."

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