Jurors said Monday that they could not reach a unanimous verdict in the case of a former CIA officer accused of leaking secrets about a classified operation to thwart Iran's nuclear ambitions to a New York Times reporter, but the judge urged them to keep talking.

On their third day of deliberations in U.S. District Court in Alexandria, jurors sent a note saying they have reached an impasse on several counts against 47-year-old Jeffrey Sterling, 47, of O'Fallon, Missouri. He's charged with illegally disclosing classified information to journalist James Risen, who wrote about the secret operation in a 2006 book.

Judge Leonie Brinkema gave jurors an early lunch break but urged them to continue deliberations in the afternoon. Outside jurors' presence, she told lawyers that she is inclined to accept a partial verdict if the jury again sends back a note claiming an impasse. She said she is not inclined to force them to deliberate beyond Monday.

The jury's note implies that it has reached a verdict on some counts, but it is unclear whether those are convictions or acquitals. Sterling faces nine counts in all -- six of which charge him with the disclosure or attempted disclosure of national defense information. One count alleges unlawful retention of national defense information. Another count charges him with illegally conveying government property and a final count alleges obstruction of justice.

Prosecutors say Sterling wanted to expose an operation to funnel deliberately flawed nuclear blueprints to the Iranians to get back at the agency for perceived mistreatment.

Defense lawyers say Senate staffers who had been briefed on the project were more likely the source of the leak.