VIENNA — With three Americans long held in Iran flying to Europe on Sunday, President Obama urged young Iranians to “pursue a new path” with the West as he imposed modest new sanctions on the country for banned missile tests.
The images of long-delayed freedom and Washington’s double-edged message underscored the uncertainties about the long-term implications of a dizzying 48 hours of diplomacy between Washington and Tehran that yielded a mutual prisoner release. It had hints of a budding era of détente. But there were clearly forces in both capitals arguing against any form of cooperation.
In Tehran, Iranians Play Down MilestoneJAN. 16, 2016
By the end of the weekend, the three Americans — a Washington Post reporter, a former Marine and a pastor — were at an American air base in Germany undergoing medical examinations, almost home after languishing in Iran’s worst prisons. The Iranians, for their part, were trying to adjust to a new world in which they were free to sell their oil around the world, but at prices far lower than they had anticipated, and to reconnect with a global financial system that had been closed off to them while they were expanding their nuclear infrastructure.
And it was unclear how they would spend upward of $100 billion in newly unfrozen funds — on long-delayed social welfare projects, or on the proxy wars that have expanded Iranian influence.
Mr. Obama also announced the resolution of another argument between Tehran and Washington that dates to the Iranian revolution, this one over $400 million in payments for military equipment that the United States sold to the shah of Iran and never delivered when he was overthrown. The Iranians got their money back, with $1.3 billion in interest that had accumulated over 37 years.
But perhaps the most notable part of Mr. Obama’s statement on Sunday was its absence of triumphalism and its warning that problems with Iran over ideology, Syria and regional ambitions were not over.

The Swiss airplane that brought three American prisoners freed from Iran after landing in Geneva on Sunday. Credit Denis Balibouse/Reuters
“This is a good day,” Mr. Obama said. “We have a rare chance to pursue a new path, a different, better future that delivers progress for both our peoples and the wider world. That’s the opportunity before the Iranian people. We need to take advantage of that.”
It mirrored the words of Hassan Rouhani, the Iranian president, who, at a news conference in Tehran, wondered aloud whether the United States would take advantage of the opening. He did not mention the prisoner release or the dismantling of a nuclear infrastructure that Iran had spent billions building up.
“This success is the result of resistance, integrity, unity and linkage between different branches and pillars of the system,” he said. “Everybody is happy except the Zionists, the warmongers who are fueling sectarian war among Islamic nations, and the hard-liners in the U.S. Congress.”

Members of Iran’s Parliament kissed Mohammad Javad Zarif, the Iranian foreign minister, during a legislative session on Sunday after international sanctions against Iran were lifted. Credit Abedin Taherkenareh/European Pressphoto Agency
With critics of Mr. Rouhani saying that the latest sanctions reveal Washington’s true stripes, and elections looming in Iran, Mr. Rouhani has to make the case that his outreach to the United States brought tangible economic benefits. With Republican presidential candidates denouncing the prisoner release, Mr. Obama has to make the case that his decision to negotiate created a channel of communication that is in America’s interest. On Sunday, he took a swipe at his critics, recalling Iran’s seizure of Navy boats and sailors last week.
“When our sailors in the Persian Gulf accidentally strayed into Iranian waters,” he said, “that could have sparked a major international incident. Some folks here in Washington rushed to declare that it was the start of another hostage crisis.” Instead, he said, a few phone calls were made and the United States “secured the release of our sailors in less than 24 hours.”
Mr. Obama and Secretary of State John Kerry, who orchestrated the events over the weekend, decided several weeks ago to delay the imposition of sanctions against Iranian companies and individuals for two missile tests, one in October and another in November, that had violated United Nations resolutions.

Mr. Obama had vowed to continue to apply non-nuclear sanctions, even after last summer’s nuclear agreement was signed. But State Department officials worried that the prisoner release would be imperiled if the sanctions were announced before the swap was arranged. “We didn’t know how big the risk was,” one senior official said. “But it wasn’t trivial.”
While the appearance of the back-to-back sanctions announcements — lifting nuclear sanctions and adding missile sanctions — might seem to suggest that Washington was merely recategorizing old penalties, they are actually not comparable.
The lifting of nuclear sanctions on Saturday allowed Iran to re-enter the world’s oil markets; according to some estimates, by the end of the year its exports may increase by a million barrels a day, yielding about $30 million a day in revenue at current prices. Its ships will be able to enter and leave foreign ports, and its citizens will have access to global financial markets.
The new sanctions are aimed mostly at individuals and some small companies accused of shipping crucial technologies to Iran, including carbon fiber and missile parts that can survive re-entry forces. Because the sanctions are focused on those individuals and firms, most Iranians will never feel them, and the penalties are comparatively tiny.
The departure of three of the freed Americans — Jason Rezaian, Amir Hekmati and Saeed Abedini — came after a tense day in which the Swiss aircraft sent for them sat on the tarmac in Tehran. The main issue was the American insistence that Mr. Rezaian’s wife, Yageneh Salehi, and his mother be able to fly out with him. They were eventually allowed on the plane.
Mr. Rezaian, The Post’s Tehran correspondent, was arrested in July 2014 on vague charges that included spying. The 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 said he had received a call from Mr. Obama expressing concern for his brother’s well-being.
The fourth American freed in the exchange, Nosratollah Khosravi — whose incarceration had not been reported until the prisoner deal was announced on Saturday — was not on the plane, American officials said. He chose to stay in Tehran, where he has an apartment. A fifth American, Matthew Trevithick, left Iran on Saturday after being freed under an arrangement separate from the prisoner exchange.
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 statement said. “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.
In a memo on Sunday to the Washington Post staff, Martin Baron, the executive editor, and Douglas Jehl, the foreign editor, reported that they had had a brief conversation with Mr. Rezaian, who was catching up on the news reports about his release on his mother’s iPad. “Asked how he was doing,” the memo said, he responded, “I’m a hell of a lot better than I was 48 hours ago.”
David E. Sanger reported from Vienna, Rick Gladstone from New York, and Thomas Erdbrink from Tehran. Peter Baker contributed reporting from Washington.