A former US defence department analyst has been sentenced to 12 years and seven months in jail for disclosing classified information.
Franklin has been co-operating with the prosecution
Lawrence Franklin passed information to an Israeli diplomat and two pro-Israeli lobbyists about a Middle East country.
No details were given, but that country is believed to be Iran.
Franklin has agreed to co-operate with the prosecution in a separate case against the two lobbyists, and could have his sentence reduced as a result.
'Seeking to help not harm'
The sentence Franklin received was already at the low end of the sentencing parameters for his offences.
As he handed down the sentence, US District Judge TS Ellis III said he was satisfied that Franklin had been driven by a desire to help, not damage the US.
Judge Ellis said Franklin had believed that the US National Security Council was not sufficiently worried by the threat posed by an unspecified Middle Eastern nation.
He thought that leaking information might catalyse the council into taking the threat more seriously.
Federal prosecutor Kevin DiGregory had called for a much stiffer sentence to illustrate the severity of Franklin's actions.
"The danger of such unauthorised disclosure, when you disclose national defence information ... is that the United States government loses control of such information," he said.
Freed on bail
Franklin, a policy analyst whose field of expertise included Iraq and Iran, was also fined $10,000 (£5,600).
He was accused of passing information to Steven Rosen and Keith Weissman of the American Israel Public Affairs Committee (Aipac) from 2002 to 2004.
The 58-year-old said he had hoped the lobbyists would use their contacts to get policies he was unhappy with changed.
The two Aipac officials have pleaded not guilty to conspiring to communicate the information given to them by Franklin and are due to go on trial in April.
Franklin has been freed on bail until their prosecution case is concluded.
Lawyers acting for the pair argue they were carrying out routine lobbying work and that conversations they had with Franklin are protected under the First Amendment's free speech guarantees.
Aipac has fired the two men and denied any wrongdoing.
Franklin also said he had met the political officer from the Israeli embassy at least nine times during the same period.
But he said he believed the Israeli government was already in possession of the information he disclosed and that he always received more information from the diplomat than he passed on.
A senior Israeli official denied that Israel had operated Franklin as a spy.
"Israel is not spying in or against the United States," said Yuval Steinitz, chairman of the Israeli parliament's Defence and Foreign Affairs Committee.
"The conviction doesn't accuse Israel of activating Franklin or tempting him," said Mr Steinitz.
BBC Pentagon correspondent Adam Brookes says the case has sent a chill through Washington.
It has made American officials more sensitive than ever about what they say on the subject of foreign policy and to whom they say it, and it has raised the question of just how much Israel conducts espionage against its greatest ally, the US, our correspondent adds.