Four Guantanamo Bay detainees have been released and sent home to Afghanistan, the Pentagon has revealed.
The men, who were held at the US military prison for over a decade, were flown to the Afghan capital Kabul overnight on a US military plane.
Shawali Khan, Khi Ali Gul, Abdul Ghani and Mohammed Zahir were then handed to Afghan authorities who are not required to further detain them.
The Department of Defence said the men, all Afghan nationals, were freed after a thorough review of their individual cases.
"As a result of that review, which examined a number of factors, including security issues, these men were unanimously approved for transfer by the six departments and agencies comprising the task force," a Pentagon statement said.
According to the AP news agency, one administration official involved in the review said most, if not all, of the terrorism allegations against the men have been discarded and each is considered a low-level operative at best.
US officials said the transfer is a sign of US confidence in Afghanistan's new president Ashraf Ghani, who requested their repatriation.
They said the US worked quickly to fulfil his request as a mark of reconciliation and improved US-Afghan relations.
Their release follows the transfer of six Guantanamo detainees to Uruguay for resettlement earlier this month.
Officials, speaking on a condition of anonymity, said the Obama administration is expected to push for more transfers in the coming weeks.
President Barack Obama has vowed to close the prison, located in Cuba, citing the damage it had caused to America's image around the world. However many opposition Republicans are against the move.
The latest release has reduced the detainee population in Guantanamo Bay to 132, the lowest number to date, the Pentagon says.
Of those, 64 have been approved for transfer.
Guantanamo Bay was set up in 2002 to house suspects captured during the US "War on Terror," launched in the wake of the September 11 attacks.
Controversial new information came to light this month regarding the CIA's use of harsh interrogation methods at the facility and so-called "black" sites in Europe and Asia.
The Senate Intelligence Committee published a 480-page report detailing the agency's use of techniques including waterboarding and sleep deprivation.
Many detainees at the facility have been held for more than a decade without being charged or put on trial.
