The United States has returned four Afghans from Guantanamo Bay back to their home country.
US officials said the transfer from the detention centre is a sign of their confidence in new Afghan president Ashraf Ghani.
Administration officials said they worked quickly to fulfil his request to return the four detainees. They had been cleared for transfer as a kind of reconciliation and an indication of improved US-Afghan relations.
The Defence Department identities them as Mohammed Zahir, Shawali Khan, Abdul Ghani and Khi Ali Gul.
Eight Afghans are among the 132 detainees remaining at Guantanamo.
The move is the latest in a series of transfers as President Barack Obama tries to reduce the number of those held at Guantanamo and works toward his goal of closing the detention centre.
The move is the latest in a series of transfers during the past two months. Administration officials said more transfers are expected in the coming weeks.
Guantanamo now holds the lowest number of detainees since shortly after it opened nearly 13 years ago in the wake of the September11 2001 terrorist attacks. Those remaining include 64 approved for transfer.
Although the four Afghans have long been approved for transfer, the move sparked debate in Washington.
Defence Secretary Chuck Hagel did not immediately sign off after General John F Campbell, the top American commander in Afghanistan, raised concerns they could pose a danger to troops in the country. Administration officials say Mr Campbell and all military leaders on the ground have now screened the move.
"The United States is grateful to the government of the Islamic Republic of Afghanistan for its willingness to support ongoing US efforts to close the Guantanamo Bay detention facility," the Pentagon statement said. "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."
One administration official involved in the review said most, if not all, of the terrorism accusations against the men had been discarded and each is considered a low-level operative at best.
Before he can close Guantanamo, Mr Obama faces the challenge of working out what to do with any detainees who are not cleared for transfer - either because the United States wants to prosecute them or continue holding them because they are considered too dangerous to release.
Congress has passed legislation blocking detainees from coming to the US for detention or trial.
Some Guantanamo opponents are questioning whether the United States has the authority to continue detaining prisoners captured in the Afghan conflict after the end of combat operations at year's end.
"We will certainly expect to see legal challenges to continued detention at the end of hostilities, which is just in a couple weeks," said J Wells Dixon, an attorney with the Centre for Constitutional Rights.
Mr Dixon has assisted on the case of Khan and said hopefully he can be reunited with his father and brother after nearly 13 years at Guantanamo.
"He was sent to Guantanamo on the flimsiest of allegations that were implausible on their face and never fully investigated," Mr Dixon argued. "He never should have been there."