Robert McFarlane, who served as National Security Advisor under President Ronald Reagan, has called on President Obama to grant clemency to Jonathan Pollard.

McFarlane wrote in a Feb. 9 letter to President Obama that an affidavit filled by then Secretary of Defense Caspar Weinberger, which is often cited as the reason for Pollard’s continued incarceration, was “surely inspired in large part by his deeply held animus toward the State of Israel.”

“His extreme bias against Israel was manifested in recurrent episodes of strong criticism and unbalanced reasoning when decisions involving Israel were being made,” McFarlane wrote of Weinberger.

Pollard, who has been imprisoned since his 1985 arrest, was sentenced to life in prison in 1987 after being convicted of spying on behalf of Israel. He is said to be ill.

McFarlane wrote that the “imprisonment of Mr. Pollard for more than 26 years is more than excessive and well beyond what any court would award for the same action today. Mr. Weinberger’s unduly harsh and unwarranted severity was disgraceful and mean-spirited. It has resulted in a great injustice that I encourage you to mitigate by awarding clemency and commuting Jonathan Pollard’s sentence to time served.”

A recent push for clemency has garnered substantive support among congressional Democrats and a range of former officials of Republican and Democratic administrations.