President Obama has pledged to shut the detention centre in 2010
The US has transferred 12 detainees from its Guantanamo Bay prison camp to Afghanistan, Yemen and the Somaliland region, the Justice Department says.
Six Yemenis, four Afghans and two Somali detainees were sent to their homelands over the weekend, it said.
President Barack Obama acknowledged in November that he would miss his January deadline to close down the camp.
The US plans to send 116 detainees to their home countries or to third countries willing to accept them.
"These transfers were carried out under individual arrangements between the United States and relevant foreign authorities to ensure the transfers took place under appropriate security measures," the Department of Justice said in a statement.
"Consultations with foreign authorities regarding these individuals will continue."
Yemenis account for almost half of the 198 detainees who remain at the US military base in Cuba. But officials fear many could re-join militant groups if sent back to Yemen.
The Washington Post reported last week that the Yemeni transfers were the result of months of high-level talks with the government in Sanaa.
It said US officials are prepared to repatriate more Yemenis if the transfer goes well.
President Obama has pledged to shut the controversial detention centre in 2010, and announced last week that many of the detainees would be sent to a prison in the US state of Illinois.
Some will face trials in US criminal or military courts, while others are expected to be transferred abroad.