Four Afghans who were held for more than a decade at the U.S. military prison at Guantanamo Bay were released late Friday, the Department of Defense announced Saturday—the latest step in the Obama administration's attempt to dismantle the wartime detention center now holding 132 detainees.

According to officials, action was taken at the request of the new Afghan president, Ashraf Ghani, in the hope of building stronger relations between Washington and Kabul. Of the detainees the U.S. has released over the last several years, it was the first time any had been repatriated to Afghanistan.

"The United States is grateful to the government of the Islamic Republic of Afghanistan for its willingness to support ongoing U.S. efforts to close the Guantanamo Bay detention facility," the Pentagon said in a statement. "The United States coordinated with the government of the Islamic Republic of Afghanistan to ensure these transfers took place consistent with appropriate security and humane treatment measures."

It is not expected—and there is no U.S. requirement—that the government of Afghanistan will continue to detain the men, identified as Mohammed Zahir, Shawali Khan, Abdul Ghani and Khi Ali Gul. A government-appointed group, the Afghan High Peace Council, noted Saturday that the men "will be reunited soon with their families" after being flown overnight aboard a U.S. military plane.

Earlier this month, six detainees—four Syrians, a Tunisian and a Palestinian—were released to Uruguay. In May, months after the deal had been reached with Uruguay for the resettlement, Hagel acknowledged his reservations over authorizing the release of the detainees. "My name is going on that document. That's a big responsibility," Hagel told The New York Times. "What I'm doing is, I am taking my time. I owe that to the American people, to ensure that any decision I make is, in my mind, responsible."

In Kabul, the U.S. Embassy said in a statement that it had "full confidence in the Afghan government's ability to mitigate any threats these individuals may pose and to ensure that they are given humane treatment" and that the transfer "demonstrates Afghan sovereignty and U.S. trust in the strength of Afghan government institutions."

Obama has struggled to move forward on his pledge to shutter the prison at Guantanamo Bay since taking office. Congress blocked its closing, banned sending prisoners to the U.S. for any reason and imposed restrictions on where they could be sent abroad. After the resettlement of the four Afghan detainees, the U.S. still holds 63 men who have been cleared for release but the U.S. has been unable to negotiate a host country for them or repatriate them in their home country.