Iran released a US Navy veteran held for almost two years after mediation by the Swiss government, American officials said on Thursday.
US President Donald Trump tweeted that Michael White had left Iran on a Swiss government aircraft, landed in Zurich and would soon be reunited with his family at home.
US special envoy for Iran Brian Hook flew to Zurich with a doctor to meet Mr White and accompany him back to America.
"For 683 days my son Michael has been held hostage in Iran by the IRGC and I have been living a nightmare," his mother Joanne White said.
"I am blessed to announce that the nightmare is over and my son is safely on his way home."
US Secretary of State Mike Pompeo commended Mr Hook for negotiating Mr White's release with the Iranians.
Mr Pompeo also praised the Swiss government and US diplomats for securing the veteran's release.
"While we are pleased that Iran was constructive in this matter, there is more work to do," he said.
"The United States will not rest until we bring every American detained in Iran and around the world back home to their loved ones."
Iranian scientist Cyrus Asgari returned to Iran on Wednesday after being released by the US, where he had spent nearly three years in detention after being charged with espionage.
Mr Asgari, 59, who has been cleared by US judicial authorities, fell into the arms of his relatives on his arrival at Tehran's international airport, Iranian media showed.
He was wearing a face mask but appeared to be in good health despite having caught the coronavirus while in US custody, the Iranian Foreign Ministry said.
"As soon as I arrived in the United States on June 21, 2017, I was arrested by the FBI," Mr Asgari told state television.
"The reason given for my arrest was a charge of stealing commercial documents.
"The legal proceedings concerning my case took two and a half years. Finally, a federal judge acquitted me."
A US court had in November cleared him of stealing trade secrets in 2016 while he was on an academic visit to Ohio from Tehran's Sharif University of Technology.
Iranian Foreign Ministry spokesman Abbas Mousavi on Tuesday denied Mr Asgari's release was part of a prisoner exchange.
Mr Mousavi said "he was freed after being exonerated", adding that his return was delayed because he was infected with Covid-19.
But Ken Cuccinelli, the acting deputy secretary of US homeland security, tweeted that the US had been "trying to deport" Mr Asgari since last year but had been "stalled every step of the way by the Iranian government".
Iran and the US hold several of each other's nationals and they have recently called for them to be released amid the Covid-19 pandemic.
Iran is holding at least five Americans and the US had a minimum of 19 Iranians in detention before Mr Asgari's release, a list compiled by AFP shows.
Tension between Tehran and Washington increased in 2018, after Mr Trump withdrew the US from a nuclear agreement between Iran and world powers, and reimposed crippling sanctions.
In December, Iran freed Xiyue Wang, a US academic, in exchange for scientist Massoud Soleimani, and said it was open to further swaps.
Americans and dual nationals known to be held by Iran include Siamak Namazi and his father Baquer, Morad Tahbaz, Gholam Shahini and Karan Vafadari.
Most of the Iranians held in the US are dual nationals charged with evading sanctions by exporting goods to Iran or using the US financial system.
