Tehran: A Swiss plane carrying Americans freed by the Iranian authorities departed Tehran on Sunday morning, a day after Iran and the United States concluded delicate negotiations on a prisoner exchange tied indirectly to the completion of a nuclear agreement.
Relatives of three of the freed Americans — Jason Rezaian, Amir Hekmati and Saeed Abedini — expressed joy after getting phone calls from the State Department that their family members were en route to Switzerland and then on to an American air base in Germany.
The fourth American freed in the exchange, Nosratollah Khosravi — whose incarceration had not been reported until the prisoner exchange was announced Saturday — was not on the plane, American officials said. It was not immediately clear why.
On Sunday, a senior United States official said that “our detained U.S. citizens have been released and that those who wished to depart Iran have left.” The Washington Post also released a statement confirming that Mr. Rezaian, a reporter for the newspaper, and his wife, Yeganeh Salehi, had left Iran.
Iran’s president, Hassan Rouhani, did not address the prisoner swap on Sunday. At a news conference, he said that since the sanctions were lifted, the door had opened for foreign investments in the country, even by American companies.
“They can invest here anytime, but they have their own obstacles to do so,” Mr. Rouhani said. He did not comment on whether the lifting of the sanctions after two years of talks with world powers, including the United States, would lead to more cooperation by Iran in Syria. Instead, he promised Iran a new and better future.
The family of Mr. Hekmati, 32, a former Marine incarcerated in Iran longer than any of the others, issued a statement expressing relief that he was out of Iran.
“It is hard to put into words what our family feels right now,” the family said. “But we remain in hopeful anticipation until Amir is in our arms.”
The family of Mr. Rezaian, 39, the Washington Post’s Tehran correspondent, also expressed enormous relief after an agonizing 24 hours between when the exchange was publicly disclosed and when they received confirmation that the Americans had left.
Mr. Rezaian was arrested in July 2014 on vague charges that included spying. The Washington Post and news media advocates around the world defended his innocence and protested increasingly loudly about his case.
“I am incredibly relieved that Jason is on his way home,” Mr. Rezaian’s brother, Ali Rezaian, said in a statement. “He is a talented journalist, who was simply doing his job fairly, accurately and lawfully.”
He added: “Today is an incredible day for all of us.”
Naghmeh Abedini, the wife of Mr. Abedini, a 35-year-old pastor from Boise, Idaho, said she had been up all night awaiting the State Department’s phone call. “They have finally left Iranian soil!” she said in a text message.
She said that she and members of the Rezaian and Hekmati families were planning to meet with their loved ones in Germany over the next few days.
An American who had been arrested several weeks ago in Tehran, where he was studying Farsi, also was freed to leave the country as part of the negotiations to free the other Americans. The arrest of that American, Matthew Trevithick, had not been publicly disclosed until the prisoner exchange was announced on Saturday.
The United States released seven Iranians held on sanctions violation charges as part of the prisoner exchange and rescinded international arrest warrants on 14 others.
The Iranian authorities considered the Americans released in the exchange to be Iranian citizens because of their dual nationalities. Publicly, government officials in Iran said they were not legally obligated to afford the prisoners the same rights given to other foreigners arrested in the country.
The exchange went a long way toward resolving an increasingly emotional side dispute between the two countries, one complicated by a legacy of hostility and mistrust built over the 35 years since the Islamic Revolution and the American hostage crisis in Tehran, where 52 Americans were held for 444 days.
Nonetheless, at least one other American, Siamak Namazi, a business consultant, remained held in Iran. He was arrested in October for unclear reasons. American officials have said they are still working to have him released.
Mr. Trevithick’s departure from Iran was handled separately, and he was not on the Swiss plane, his family said.
The New York Times