DOHA — Iran handed over roughly 40 detained foreigners and the remains of fallen American service members in a Qatar-brokered exchange Saturday, the most concrete confidence-building measure since a ceasefire halted six weeks of open warfare across the Middle East. In return, the United States and Israel released a smaller group of Iranian nationals and detainees linked to Hezbollah, officials said, completing a swap that had been quietly negotiated alongside the Islamabad ceasefire talks.

The exchange took place in stages at a military airfield outside the Qatari capital, beginning before dawn and stretching past midday, according to two diplomats with knowledge of the choreography. Qatari Foreign Minister Mohammed bin Abdulrahman Al Thani, who has shuttled between Tehran and Western counterparts since late March, oversaw the handover personally. The Red Crescent and the International Committee of the Red Cross verified identities on both sides, the diplomats said.

“This is the test of whether words spoken in Islamabad become deeds on the tarmac,” Al Thani told reporters in a brief statement after the final flight departed Doha. “Today, on both sides, families have been answered. There is much more to do.”

Among the freed foreigners were citizens of the United States, the United Kingdom, France, Germany, Canada, Australia, Sweden and the Netherlands, as well as dual nationals from Lebanon and Iraq. Several had been held for years on espionage or security charges that Western governments long described as politically motivated. Others were detained after the war began on March 1, including journalists, aid workers and at least three crew members from a Liberian-flagged tanker that Iran’s Revolutionary Guard Corps seized in the opening days of the conflict.

A senior State Department official, speaking on condition of anonymity to discuss intelligence matters, said the remains of nine American service members were transferred to a U.S. military mortuary team at the airfield. Eight were killed in Houthi missile strikes against bases in the region; the ninth, a Navy petty officer, died when a small craft attacked a destroyer in the Gulf of Oman during the second week of fighting. “We will not leave our people behind, in life or in death,” the official said. “This was a long road, and it is not finished.”

President Donald Trump, in a written statement issued through the White House, called the swap “a great moment for American families” and credited “tough talks and tougher resolve.” Israeli Prime Minister Benjamin Netanyahu’s office, in a more cautious statement, described the exchange as “a humanitarian step that does not erase the threats that still exist,” and reiterated that Israel reserved the right to act against any future Iranian nuclear reconstitution.

Iranian state television broadcast images of the released Iranians, who included three men described as engineers detained in 2023 on U.S. export-control charges and a woman identified as a graduate student held in Europe. Foreign Minister Abbas Araghchi, speaking from Tehran, said the swap “was a matter of dignity, not bargaining,” and accused Western governments of having used detainees as leverage for years. He did not address questions about Hezbollah-affiliated prisoners released into Lebanese custody.

Two Lebanese security officials confirmed that a separate handover took place at a checkpoint south of Beirut early in the afternoon, where four men described by Israel as facilitators of weapons transfers were released. A fifth detainee, held in connection with a 2024 plot against an Israeli diplomat in Cyprus, was not part of the swap and remains in Israeli custody, the officials said.

Notably, the exchange did not include any provision for a tribunal or formal accountability mechanism for wartime actions, a question that had complicated the Islamabad talks. Diplomats said that issue had been deliberately set aside to allow the immediate humanitarian step to proceed.

“You cannot do everything at once,” said Layla Hassan, a Beirut-based regional analyst. “What Doha did today is the easy part, comparatively. The harder part — verification, the future of Iran’s nuclear program, the disposition of militia arsenals in Iraq and Yemen — has barely begun. But getting bodies home and getting hostages out builds a small reservoir of trust, and right now that reservoir is nearly empty.”

The exchange came three days after the ceasefire took effect at midnight GMT on April 15 and amid two minor violations earlier in the week — a Houthi missile launch toward shipping in the Red Sea that was intercepted and a rocket fired from Iraqi territory that landed in open desert. Both were condemned by all parties to the Islamabad framework, which includes the United States, Israel, Iran, Saudi Arabia, Egypt and Pakistan as guarantor.

U.N. Secretary-General António Guterres, in a statement from New York, urged “all parties to use this momentum to address the underlying drivers of the conflict, including the protection of civilian shipping in the Strait of Hormuz and the safeguarding of nuclear sites.” A U.N. observer mission deployed to the strait this week is expected to file its first interim report by the end of the month.

Inside the United States, the swap drew bipartisan approval, with Senate Foreign Relations Committee members from both parties welcoming the return of American remains while several Republicans cautioned against treating the exchange as a substitute for what they called “verifiable Iranian concessions.” Families of the returned service members were flown to Dover Air Force Base, where a dignified transfer was scheduled for Sunday morning.

A second tranche of detainees, including at least six foreign nationals still held in Evin Prison, is expected to be released within ten days if the ceasefire continues to hold, according to a Qatari official familiar with the negotiations. Officials said additional steps, including arrangements for civilian air corridors and the resumption of limited consular contacts, would be announced in the coming weeks.