On Saturday, a significant milestone was marked as Iran and Sweden swapped prisoners, bringing solace to families while sparking worries about succumbing to Tehran’s strategy of seizing foreign nationals on fabricated charges to secure concessions.

The European Union diplomat and Swedish citizen, Johan Floderus, who was detained in Tehran in April 2022, and Saeed Azizi, a dual national captured in 2023, were set free by Iran, as confirmed by Swedish Prime Minister, Ulf Kristersson, in a social media announcement.

In return, Sweden released Hamid Nouri, an Iranian judiciary official who had been convicted of torture, war crimes, and the mass execution of 5,000 dissidents in 1988 by a Swedish court.

The release of Mr. Nouri was disclosed by Kazem Gharibabadi, Iran’s deputy judiciary minister and secretary general of the High Council for Human Rights, who expressed delight in sharing the news of Mr. Nouri’s return to Iran.

Oman facilitated the exchange, with prisoners from both countries being held there before being repatriated.

A relative of Mr. Floderus mentioned that the diplomat was en route to Europe from Oman on Saturday afternoon.

The release brought joy to the families of the Swedes and caught the attention of officials closely monitoring the situation.

“I am happy to hear that our Swedish colleague Johan Floderus and his compatriot Saeed Azizi have been freed from unjustified Iranian detention,” mentioned the president of the European Commission, Ursula von der Leyen.

The arrest of Mr. Floderus by Iran in April 2022 was initially kept confidential by Sweden and the European Union until it was exposed by The New York Times in 2023, over 500 days later.

However, the prisoner exchange, particularly Sweden’s release of Mr. Nouri, sparked outrage and fear over rewarding Iran for its systematic detainment of foreigners on false charges to extract concessions from Western nations.

Mr. Nouri’s case was seen as a pivotal legal precedent for prosecuting war criminals beyond their home borders, establishing accountability for atrocities against humanity. At that time, human rights lawyers believed his case could set the stage for holding officials from other countries like Syria, Sudan, and Russia accountable for war crimes.

Mr. Nouri, an official at Gohardasht Prison in Tehran, played a key role in the mass executions of 1988. He was responsible for preparing lists of individuals to be executed by a death committee, which included Ebrahim Raisi, and escorting them to their fate.

The news of the prisoner swap left families of the remaining detainees worldwide, including Ahmadreza Djalali – a Swedish scientist on death row in Iran, protesting the exchange on social media. Mr. Djalali has consistently denied the accusations against him.

Mariam Claren, daughter of Nahid Taghavia, a German-Iranian detainee in Tehran, expressed shock at the exchange, highlighting Mr. Nouri’s involvement in political killings in the past.

Richard Ratcliffe, husband of Nazanin Zaghari-Ratcliffe, a British-Iranian detainee in Iran for years on false charges, emphasized the intricacies of such prisoner swaps.

While celebrating Johan and Saeed’s freedom, Mr. Ratcliffe lamented for Ahmadreza and the others left behind, stating that hostage diplomacy is inherently unjust.

Olivier Vandecasteele, a Belgian aid worker formerly detained in Iran alongside Mr. Floderus, described the bittersweet feelings that come with such exchanges.

“The release of hostages brings mixed emotions of joy and sorrow,” he remarked. “While some are set free, the fate of others remains uncertain. Families awaiting the return of their loved ones are enduring a poignant moment today.”

The prisoner exchange does not address the plight of numerous Iranians wrongfully detained by their government.

For Iran, the return of Mr. Nouri from Sweden signifies a significant achievement. His arrest in 2019 upon arrival in Stockholm under universal jurisdiction was considered a major breakthrough in international law enforcement against war crimes.

Mr. Nouri was convicted of war crimes by a Swedish court in 2022, and he was in the process of appealing this verdict at the time of his release.

Reporting from Riyadh, Saudi Arabia was contributed by Vivian Nereim and Farnaz Fassihi reported from New York.