U.S. State Department Spokesman Philip Crowley responded Tuesday to Prime Minister Benjamin Netanyahu's decision to issue a formal public request to the U.S. president for the release of Jonathan Pollard, saying only that the convicted spy currently remains in prison.

"Prime Minister Netanyahu has raised this from time to time, both in his current incarnation and in his previous incarnation,' Crowley said, adding that "all I can tell you is Jonathan Pollard remains in prison".

"If the prime minister wants to raise this with the United States government again, obviously it is his option to do so," he added.

If Netanyahu issues the request, it will mark the first formal appeal by Israel for the release of Pollard.

Earlier, White House Spokesman Robert Gibbs said that he was not aware that U.S. President Barack Obama was considering the possibility of granting clemency to Pollard.

Pollard was sentenced to life in prison in 1987 on charges of spying on the U.S. for Israel. He is incarcerated at a federal jail in North Carolina.

On Monday, Netanyahu met with Pollard's wife Esther, as well as Lawrence Korb, who was the U.S. assistant secretary of defense at the time of Pollard's arrest.

The two brought to Netanyahu a letter from Pollard asking that Israel formally request his release.

Korb said that such a request could lead to Pollard's release.

Netanyahu raised the concern that a public request could in fact hurt efforts to release Pollard. Esther Pollard and Korb said that it was a risk worth taking.

After consultations on Monday night and Tuesday morning, Netanyahu decided to send a formal letter to Obama on the matter.

"I intend to continue to act with determination for the release of Pollard, both because of the State of Israel's moral obligation to him and so that he can live with his family and restore his health after his prolonged incarceration," Netanyahu said in a statement on Tuesday.

This past October, Korb had said that Pollard should be freed since his punishment was too severe relative to the felonies he committed. He also pointed out that Pollard has been sitting in prison longer than any other person who has been charged with spying for a friendly country on the U.S.

The reason for Pollard's severe punishment, Korb explained in a piece written for the Los Angeles Times, was due to a letter that the U.S. Secretary of Defense at the time gave to the court directly before Pollard's sentencing.

In the letter, Secretary of Defense Caspar Willard Weinberger detailed the damage that Pollard caused to the national security of the U.S., including an apparent connection with the exposure and subsequent killing of 11 American agents in the former USSR. According to Korb, the letter demanded that Pollard be severely punished. In Korb's article, he says the thinking that any of Pollard's information had reached the USSR has been debunked.

Speaking to Haaretz on Tuesday, Korb reiterated his remarks made earlier this year, saying. "It turned out [Pollard] didn’t leak any critical information and other people were later convicted for spying with regard to documents that rose concern. The situation is very different now," Korb said.