Former Pendleton Marine among Americans released by Iran Amir Hekmati

The Post's petition to the United Nations was part of a series of steps the paper took to publicize the Rezaian case and bring global pressure on Iran, even as the Obama administration worked privately to secure the release of Americans it asserts were unjustly imprisoned.

Rezaian, 39, one of the USA citizens freed by Iran as part of a prisoner swap this weekend, was accused by Iranians of being a spy and spent 18 months imprisoned.

"We talked a bit about his experience, but I think he was just appreciating his freedom and trying to enjoy it as much as he could", Kildee said. 'I know people are eager to hear from me but I want to process this for some time'.

Hekmati said he had resigned himself to spending 10 years in prison and the release was a surprise.

"As soon as we got out of Iranian airspace, champagne bottles were popped", he said.

Following a "frantic final round of diplomacy" involving American, Iranian and Swiss officials, all five boarded the plane, the congressman said.

"I reiterate the need to be vigilant about the deceit and treachery of arrogant countries, especially the United States, in this [nuclear] issue and other issues", Khamenei said, according to Iranian news agencies.

He was detained in 2011, weeks after arriving in Iran to visit his grandmother, according to his family's website.

Hekmati's family released a photo Monday showing him with two sisters and a brother-in-law, along with U.S. Rep. Dan Kildee, D-Michigan.

Hekmati was released at the weekend along with four other Americans in a deal negotiated between Washington and Iran.

'The Iranians, as they have done all along, continued to manipulate them, continued to try and mess with them and prevented Yeggie from leaving for some period of time, ' Ali Rezaian told CNN in an interview from outside a U.S. military hospital in Landstuhl, Germany.

"Expressions by some US politicians in recent days are matter of pessimism", Khamenei said without elaborating.

"I was anxious that maybe the Iranian side was going to make new demands at the last minute or that the deal wasn't going to work out, so up until the last second we were all anxious and concerned", he said.

An appeals court later commuted the sentence to a 10-year jail term.

Washington Post Executive Editor Martin Baron and Foreign Editor Douglas Jehl said Rezaian "looked good" during their two-hour meeting in a conference room at the Landstuhl Regional Medical Center near the Ramstein Air Base. Hekmati's family members are with them.

White House spokesman Josh Earnest said Tuesday that USA officials believe Robert Levinson, who disappeared in Iran in 2007 while working for the CIA on an unapproved intelligence mission, may no longer be in that country. All are dual U.S.-Iranian nationals, as was a fourth freed prisoner who opted to stay in Iran.

Rezaian said he spent most of his time in the custody of Iran's Revolutionary Guard - the military force tied to hardline religious leaders.

The Iranian Foreign Ministry said in a statement: "Iran's missile program has not been designed for carrying nuclear weapons at all, and therefore it doesn't violate any worldwide rule".