Jonathan Jay Pollard, a former U.S. naval intelligence analyst and convicted Israeli spy, was given a life sentence in 1986 in a case that has since become a sore spot in U.S.-Israeli relations.

The sentence itself is one source of contention. Pollard currently is the only person ever to have received life imprisonment for spying during peacetime, and he also may be the only person to receive that sentence for spying on behalf of a strategic ally, according to the Mideast Quarterly.

In addition, Pollard didn’t stand trial for his crime but instead accepted a plea bargain. Pollard has since claimed that federal prosecutors agreed not to pursue a life sentence but did so anyway. He currently is serving his sentence -- with recommendation against parole -- in a federal prison in North Carolina.

Pollard maintains his espionage did nothing to endanger American security.

In a letter published in the Wall Street Journal, Pollard claimed he only gave Israel information regarding an "Iraqi poison gas threat to Israel" and surrendered no US codes, agents, or classified military technology in the process. His sole motives were to protect Israeli security, he said.

Intelligence community leaders, however, say Pollard did far more damage to American security than was publicly disclosed, according a New Yorker magazine article. Many officials even said the information Pollard released ultimately wound up in Soviet hands.

After 13 years of denials, Israel in 1998 finally acknowledged that Pollard had been a spy and awarded him Israeli citizenship, something his lawyer thought would help his chances for a pardon, the BBC reported. But Pollard's efforts to reduce his sentence, withdraw his plea or secure a presidential commutation have all been rejected.

Ron Olive, the primary investigator in the case, wrote in his book "Capturing Jonathan Pollard" that besides Israel, the Texas-born spy offered classified material to four other countries, including Pakistan.

Pollard's sentence has drawn the attention of seven defense secretaries, each of whom has written a petition urging that he remain imprisoned for life.

Former CIA chief George Tenet, in his memoir "At the Center of the Storm: My Years at the CIA," claimed that he threatened to resign if President Clinton commuted Pollard's sentence.