Former US Navy intelligence analyst Jonathan Pollard will be released on November 21 after serving 30 years in prison for spying for Israel.
The decision, revealed Tuesday, caps a sensational case that has troubled relations between the United States and its closest Middle East ally for more than three decades.
November 21 marks the earliest date Pollard could be eligible for parole, but officials insisted the release was not a sop to Israel, still smarting over the Iran nuclear deal.
Secretary of State John Kerry denied the release was linked to the July 14 deal, which is supposed to restrain Tehran's nuclear ambitions but which Israel vehemently opposed.
"No, no, no. Truthfully. I haven't even had a conversation with them," he told reporters.
Pollard's lawyers, Eliot Lauer and Jacques Semmelman, also insisted: "The decision is not connected to recent developments in the Middle East."
"The decision to grant parole was made unanimously by the three members of the Parole Commission, who make their decisions independently of any other US government agency," they said.
Israeli Prime Minister Benjamin Netanyahu welcomed the news and said he looked forward to the release.
"Throughout his time in prison, I consistently raised the issue of his release in my meetings and conversations with the leadership of successive US administrations," he said.
Israeli Justice Minister Ayelet Shaked went further in a message on her Facebook page, and took the opportunity to attack the nuclear deal.
"Great joy," she wrote.
"Thirty years of suffering will come to an end this November; not though kindness but through the law. Not because of the devastating agreement between the United States and Iran but because of the law."
The case has been a major thorn in US-Israeli relations since Pollard was arrested for passing secrets to the Jewish state in 1985.
He pleaded guilty in 1987 to spying for Israel while he worked for US Navy intelligence.
Two years after his arrest in 1985, he was sentenced to life in prison, the only American ever to receive such a heavy sentence for passing classified information to a US ally.
A cause celebre
It made him a cause celebre for many Israelis, but US officials have adamantly opposed clemency until now, contending the damage he did was far more severe than publicly acknowledged.
He was arrested on November 21, 1985, while trying in vain to seek asylum at the Israeli embassy in Washington, but Israel did not admit Pollard spied for it until 1998.
In a jailhouse interview with journalist Wolf Blitzer in 1987, Pollard claimed that he had provided Israel with reconnaissance imagery of Palestine Liberation Organization headquarters, intelligence on Libyan air defenses and on Arab and Islamic military activities.
US prosecutors alleged he was motivated as much by money as support for the Jewish state, having been paid $10,000 in cash, thousands more in jewels and expenses, and a $2,500 a month salary by Israel.
Pollard's first wife Anne, who was sentenced to five years along with her husband, was released after three-and-a-half years. The couple divorced after her release.
Justice Department spokesman Marc Raimondi confirmed that the government had not opposed parole.
"The Department of Justice has always maintained 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, ending November 21, 2015," he said.
Pollard's lawyers said they were notified by the Justice Department on July 1 that it would not seek denial of parole at his July 7 parole hearing at the federal prison in Buttner, North Carolina where he is held.
They said they had shown that Pollard had an exemplary prison record and that there was no possibility he would commit any further crimes, the standard for obtaining parole.
Had parole been denied, Pollard would have had to serve another 15 years in prison.
Pollard was looking forward to being reunited with his second wife Esther, a Canadian who campaigned for his release, his lawyers said.
"Mr Pollard would like to thank the many thousands of well-wishers in the United States, in Israel, and throughout the world, who provided grassroots support by attending rallies, sending letters, making phone calls to elected officials and saying prayers for his welfare. He is deeply appreciative of every gesture, large or small," they said.
Under the terms of his parole, he may be required to stay in the United States for five years, but Obama can authorize his release sooner and allow him to move to Israel immediately, his lawyers argued.
"We respectfully urge the president to exercise his clemency power in this manner," they said.