Updated at 10:45 a.m. ET

The United States has released four Afghan detainees from the U.S. military prison at Guantanamo Bay, Cuba, who were returned to Afghanistan — the latest in a series of releases of inmates in recent weeks.

Reuters says: "The men were flown to Kabul overnight aboard a U.S. military plane and released to Afghan authorities, the first such transfer of its kind to the war-torn country since 2009, a U.S. official said."

The four were released at the request of Afghanistan's new president, Ashraf Ghani, The Associated Press reports.

The AP says:

"Obama administration officials said they worked quickly to fulfill the request from Ghani, in office just three months, to return the four, who had been cleared for transfer as a kind of reconciliation and mark of improved U.S.-Afghan relations."There is no requirement that the Afghan government further detain the men, identified as Mohammed Zahir, Shawali Khan, Abdul Ghani and Khi Ali Gul."

In a Pentagon statement, the U.S. said it 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 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."

Even so, The Washington Post reports: "The United States and Afghanistan have not started serious discussions about repatriating the remaining eight Afghans still held at Guantanamo Bay, said the official, speaking on the condition of anonymity because of the sensitivity of the transfers.

Last month, five Guantanamo detainees, four of them Yemenis, were sent to Georgia and Slovakia. And, earlier this month, the U.S. transferred six inmates to Uruguay.The latest release comes as no real surprise, as it is part of a larger U.S. effort to draw down the inmate population at Guantanamo, which President Obama, in his first campaign for the White House, promised to close.

Carol Rosenberg, who covers Guantanamo for The Miami Herald, tells NPR that Ghani formally requested the four be transferred "because they were at the front of the queue, meaning they were on a list that was approved a long time ago. So, it was easier to get them out than, say, the other eight Afghans are still at Guantanamo.

"In January 2010, the Obama administration drew up a list of people who would be approved for release," Rosenberg says. "These four men were on it, along with dozens of others. Many of them had previously also been approved for release during the Bush years.

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