Prosecutors say a former CIA officer exposed one of the agency’s top assets by leaking details of a covert operation in Iran to a New York Times reporter.

The long-delayed leak trial of ex-CIA man Jeffrey Sterling of O’Fallon, Missouri, began Tuesday in federal court in Alexandria with jurors receiving a lesson in spycraft from CIA officers who recruited and managed a Russian nuclear expert nicknamed “Merlin.”

Prosecutors say Sterling divulged classified information to journalist James Risen about a plan to have Merlin funnel flawed blueprints to Iran to cripple that nation’s nuclear ambitions.

Defense lawyers say the government has no direct evidence proving Sterling was Risen’s source, and that the CIA focused its suspicions on Sterling because he had become an outcast for claiming racial discrimination at the agency.

(AP)