Israeli spy Jonathan Pollard could be released after serving a 30-year sentence when he becomes eligible for parole in November.
The potential release, long opposed by US officials, comes shortly after world powers concluded a major nuclear deal with Iran and could be seen as an olive branch to Israel.
But the US administration was quick to deny that the decision would have anything to do with diplomatic considerations.
Pollard was sentenced to life in prison in 1987, two years after his arrest, and is eligible for parole in November 2015 - and on Friday the Justice Department indicated that it would not oppose his release.
"The Department of Justice has always and continues to maintain that Jonathan Pollard should serve his full sentence for the serious crimes he committed, which in this case is a 30-year sentence as mandated by statute," Department of Justice spokesman Marc Raimondi said.
A National Security Council spokesman was emphatic that the timing of the release was not part of any deal.
"Mr Pollard's status will be determined by the United States Parole Commission according to standard procedures," Alistair Baskey said.
"There is absolutely zero linkage between Mr Pollard's status and foreign policy considerations."
A US-born Israeli, Pollard was sentenced to life in prison in 1987 for passing secret US intelligence on Arab and Pakistani weapons to his other homeland.
Pollard's imprisonment has been a continual thorn in the side of American-Israeli relations and the country has repeatedly asked for his release.