A New York Times reporter is expected to reluctantly testify in a trial run to see what evidence he could offer in the case of a former CIA officer accused of leaking classified information.

Federal prosecutors have said journalist James Risen is a critical witness in a case against ex-CIA employee Jeffrey Sterling. Prosecutors believe Sterling was a source for a book by Risen that detailed a botched effort to cripple Iran’s nuclear program.

A judge ordered Monday’s hearing in northern Virginia to work out in advance any snags in calling Risen to the stand.

Risen has said that to protect his sources’ confidentiality, he will refuse to answer detailed questions.

Prosecutors have subpoenaed Risen but promised to limit their questioning. Defense attorneys may also want to question him.

(AP)