• The last pieces in a controversial swap mediated by Qatar fell into place when $6bn (£4.8bn) of Iranian funds held in South Korea reached banks in Doha.
• It triggered the next step - to allow the four American men and one woman in Tehran, who are also Iranian citizens, to board a flight to Qatar's capital.
Image: BBC
Five Americans jailed for years in Iran and widely regarded as hostages are on their way home to the United States.
The last pieces in a controversial swap mediated by Qatar fell into place when $6bn (£4.8bn) of Iranian funds held in South Korea reached banks in Doha.
It triggered the next step - to allow the four American men and one woman in Tehran, who are also Iranian citizens, to board a flight to Qatar's capital.
They will be met by senior US officials and then flown to Washington.
The Americans are reported to include 51-year-old businessman Siamak Namazi, who has spent nearly eight years in Tehran's notorious Evin prison, as well as businessman Emad Shargi, 59, and environmentalist Morad Tahbaz, 67, who also holds British nationality.
The US has said its citizens were imprisoned on baseless charges for use as political leverage.
In the first indication a deal was reached, they were moved in mid-August from Evin to a safe house in Tehran.
Five Iranians imprisoned in US jails, mainly on charges of violating US sanctions, are also being granted clemency as part of this swap. Not all of them are expected to return to Iran.
They have been named by Iran as Reza Sarhangpour, Kambiz Attar Kashani, Kaveh Lotfolah Afrasiabi, Mehrdad Moein Ansari and Amin Hasanzadeh.
"The Americans' nightmare is finally over. The solitary confinement, the not knowing, the lost days, the incredibly difficult disruption to the rhythm of life," reflected Iranian-born Professor Mehran Kamrava, who now teaches at Georgetown University in Qatar.
The deal comes after months of indirect talks mediated by Qatar, which began in February last year.
A source briefed on the negotiations say there were at least nine rounds of difficult discussions in Doha, with the American and Iranian delegations staying in separate hotels. Senior Qatari officials also shuttled between Tehran and Washington.
"I think there's a little bit of a win for both sides," Prof Kamrava told the BBC in Doha. "For [US President Joe] Biden, heading into the election, he's bringing Americans home and for Iran, there's the release of Iranians in prison in the United States, but it's that six billion [dollars] that's a big win."
Iranian officials have repeatedly declared they will spend their money as they wish. But sources involved in this process insist these funds will be strictly controlled.
"No funds will go into Iran," they emphasised. "Only humanitarian transactions, including food, medicine, agriculture, paid to third party vendors, transaction by transaction."
Sources told the BBC this money was not part of Iranian assets frozen by sanctions. The money in South Korea, revenue from Iranian oil sales, had been available to Tehran for bilateral and non-sanctioned aid, but was not spent for various reasons including difficulties of currency conversion.
Leading US Republicans have denounced the deal as a ransom payment and sanctions relief. The Republican chairman of the House Foreign Affairs Committee, Michael McCaul, castigated the US government for transferring funds to "the world's top state sponsor of terrorism".
Who are the American prisoners?
- Morad Tahbaz: Arrested in 2018 along with eight other Iranian conservationists. They had been using cameras to track critically-endangered wild Asiatic cheetahs, but were accused of using their environmental projects as a "cover to collect classified information". Denied the charge but sentenced to 10 years in prison
- Siamak Namazi: Dubai-based oil executive arrested in 2015. His elderly father, Baquer, was detained the following year, after Iranian officials allowed him to visit his son. Both sentenced to 10 years in prison for "co-operating with a foreign enemy state", which they denied. Iran let Baquer leave for medical treatment in 2022
- Emad Shargi: Detained in 2018 while working for an Iranian venture capital fund. Released on bail and later told he had been cleared of spying charges. Informed by a court in 2020 that he had been convicted in absentia and sentenced to 10 years in prison. Released ahead of an appeal and reportedly detained in 2021 while trying to cross Iran's western border illegally
- The two other released Americans have not been named.
The enormous relief that some prisoners are finally coming home is tempered by the knowledge that more may be seized in future. There are still other dual nationals behind bars in Tehran.
"The Iranian government has become a hostage-taking government," explains Sanam Vakil, director of the Middle East and North Africa programme at Chatham House, a London-based think tank. "They have been using people as pawns, and that's part of their leverage against the West."
Qatar is hoping this rare moment of cooperation will help to catalyse progress on other long-standing disagreements and disputes, including the 2015 nuclear deal regarded as all but dead after the then-US president, Donald Trump, pulled out of it five years ago. Others remain sceptical.
"There is no deal or even serious talks, even though the Iranians claim they want to begin a serious diplomatic process," insists a Western official familiar with this file with barely concealed frustration. "They have taken some steps, but we have told them, through the Omanis, what they should do to set conditions for diplomacy to have a chance."
On the nuclear front, sources say Iran appears to have slowed its production of 60%-enriched uranium - a step back from weapons-grade levels of 90%, but higher than the limits agreed in the 2015 accord.
But there's still deepening concern about Iran's lack of transparency on its nuclear ambitions.
On Sunday, the director general of the International Atomic Energy Agency (IAEA), Rafael Grossi, issued a statement strongly condemning Iran's "disproportionate and unprecedented" withdrawal of more IAEA inspectors. The move, while formally permitted under the Nuclear Non-Proliferation Treaty (NPT), was called "another step in the wrong direction".
Last week in Vienna, 63 countries also co-signed a statement condemning Iran's lack of co-operation with the NPT Safeguards Agreement.
"Nobody should have any illusion this deal will positively transform the US-Iran relationship," underlines Karim Sadjadpour, a senior fellow at the Carnegie Endowment for International Peace, a Washington-based think tank.
"As long as Khamenei rules Iran, the Islamic Republic will continue to maintain strategic enmity with the United States," he says in a reference to Iran's supreme leader, Ayatollah Ali Khamenei. "It serves his interest to have an external adversary and it's part of the regime's identity."
President Biden has long been urged to bring the Americans home.
Earlier this year, Siamak Namazi wrote to him from prison, imploring him to do more to honour the promise of the former Obama administration to bring him "safely home within weeks". He described himself as having the "unenviable title of the longest held Iranian-American hostage in history".
He was arrested during a 2015 business trip to Tehran and convicted of co-operating with a hostile government - in other words, the United States. His father Baquer was also detained and convicted on the same charge when he went to Tehran to try to secure his release. But he was freed last October, ostensibly on medical grounds. The US said they were both unjustly detained.
Morad Tahbaz and his family were also left feeling angry and abandoned after receiving assurances from the British government that he would return to Britain last year along with two other British-Iranians who were detained arbitrarily, Nazanin Zaghari-Ratcliffe and Anoosheh Ashoori.
This swap comes at a time when Iran is under mounting pressure from the crippling impact of international sanctions, and a year of unprecedented protests sparked by the death in custody of Mahsa Amini, after she was detained by Iran's morality police.