The US military has sent 11 Yemeni prisoners from Guantánamo Bay to Oman to start their lives anew, the Pentagon said Monday, leaving just 15 men in prison in a bold move at the end of a Biden administration that has left the prison population smaller than ever in its more of a 20-year long history.

None of those freed during the two decades of captivity were charged with criminal offences. Now, all but six of the remaining prisoners were accused or convicted war crimes.

There were 40 inmates when President Biden took office and revived the Obama administration’s efforts to close the prison.

The Pentagon carried out an undercover operation in the early hours of Monday morning, days before Guantanamo’s most notorious prisoner, Khalid Shaikh Mohammed, was to plead guilty to masterminding the Sept. 11, 2001, attacks that killed nearly 3,000 people. in exchange for life imprisonment instead of facing the death penalty.

The handover was worked on for about three years. The initial plan to implement the transfer in October 2023 was derailed by Congress opposition.

Among them are 11 acquitted Moath al-Alwia former long-term hunger striker who attracted attention in the art world building model ships from items found in Guantánamo prison; Abdulsalam al-Hilawhose testimony was requested by the defenders in The case of the USS Cole; and Hassan Bin Attash, younger brother defendant in the 9/11 conspiracy case.

All detainees have been approved for transfer through federal national security councils.

US officials declined to say what the United States has given Oman, one of America’s staunchest allies in the Middle East, and what guarantees it has received in return. By law, the military cannot send Guantanamo detainees to Yemen because, as a nation embroiled in a brutal civil war, it is considered too unstable to monitor and rehabilitate returnees.

The United States typically pays stipends to host countries to house, educate, rehabilitate, and monitor the men’s activities. The United States has also asked receiving countries to ban former Guantanamo detainees from traveling abroad for at least two years.

Few details about the rehabilitation program have emerged from Oman, the island nation led by the sultan. Saudi Arabia has shown his reintegration center for Guantánamo prisoners to journalists and scientists, but Oman is not.

U.S. officials called the Omani program “well-rounded” and designed to help Yemenis return to society with jobs, homes and families, many through arranged marriages.

The Obama administration sent 30 prisoners to Oman from 2015 to 2017. One man died there, but the rest were sent home — 27 to Yemen and two to Afghanistan, according to a State Department official, who spoke on condition of anonymity because of the sensitivity of diplomatic negotiations.

Many Yemenis married and had children in Oman and were repatriated with their families.

Word of the successes reached the Yemeni prisoners at Guantánamo and made Oman a preferred resettlement country, he said. George M. Clarkeattorney for the two men who were transferred this week.

“It’s not just culturally compatible,” said Mr. Clarke. “This is because they have been given reasonably decent freedom and have been properly integrated into society in a successful manner. And that’s what makes resettlement work.”

The men sent to Oman were captured by US allies or taken into US custody between 2001 and 2003. Mr Clarke said they were eager to rejoin the world of mobile phones and internet access.

“They want to live their lives,” said Mr. Clarke, who represents Tawfiq al-Bihani and Mr. Bin Attash. “They want to get married. They want to have children. They want to get a job and have a normal life.”

In October 2023, a military cargo plane and a security team were already at Guantánamo Bay to transport 11 detainees to Oman when objections from Congress prompted the Biden administration to end the mission, which finally took place this week.

By that time, the prisoners who left this week had already had exit interviews with representatives of the International Committee of the Red Cross, and guards had taken personal belongings that would travel with them.

Over the next year, Tina S. Kaidanow, the Biden administration’s Guantánamo envoy, kept the deal viable through negotiations, travel and meetings within the United States government and with the recipient country, the State Department official said. Mrs. Kaidanow died in October.

Three other detainees at Guantánamo are eligible for transfer, including a stateless Rohingya, a Libyan and a Somali.

Beyond that, efforts are ongoing find a nation that will receive and provide health care for a disabled Iraqi who pleaded guilty to commanding irregular forces in wartime Afghanistan. US officials have a plan to send him to prison in Baghdad, but he is suing the Biden administration to thwart that transfer with the explanation that he would be endangered in his homeland.

The detention area of ​​Guantánamo today is an emptier, quieter place than it once was.

The remaining 15 prisoners are housed in two prison buildings with space for around 250 prisoners.

The prison was opened on January 11, 2002 with the arrival of the first 20 prisoners from Afghanistan. At its peak in 2003, the operation had about 660 prisoners and more than 2,000 soldiers and civilians commanded by a two-star general. While the prisons were being built, most of the detainees were kept in open-air cells on a cliff overlooking the water.

The operation now has 800 soldiers and civilian collaborators – 53 guards and other staff for every detainee – and is led by a junior officer, Colonel Steven Kane.

Most of those sent were repatriated to countries including Afghanistan, Algeria, Kenya, Malaysia, Morocco, Pakistan, Tunisia and Saudi Arabia. In addition, Belize has accepted a Pakistani who pleaded guilty to war crimes and became a government subcontractor. That man, Majid Khan, was joined there by his wife and daughter.