ALEXANDRIA, Va. — The Justice Department on Tuesday pressed ahead with the prosecution of a former Central Intelligence Agency official, a day after it said it would not force a reporter for The New York Times to testify at the trial.

The former official, Jeffrey Sterling, is accused of revealing a covert operation to disrupt Iran’s nuclear program, the details of which were included in a 2006 book, “State of War,” by James Risen, the Times reporter. In attempting to compel Mr. Risen’s testimony for the past seven years, the Justice Department had argued that his account was crucial to their case. But under pressure from journalism groups and advocates, Attorney General Eric H. Holder Jr. agreed not to force Mr. Risen to reveal his sources, leaving the government with a case that is largely circumstantial.

In opening arguments in Federal District Court here on Tuesday, prosecutors said that much of the information that Mr. Risen published about the Iranian operation was known only to Mr. Sterling, whom they described as a disgruntled employee who was bitter that the C.I.A. refused to settle a discrimination lawsuit he had filed. They said Mr. Sterling caused lasting harm with his disclosures.

“He struck back with the only weapon he had: secrets,” James L. Trump, one of the prosecutors, told the court.