Fifteen Guantanamo Bay prisoners have been transferred to the United Arab Emirates in the biggest such release for years.
The Pentagon said on Monday that the transfer of 12 Yemenis and three Afghans brought the total number of prisoners left in the US military-run jail in Cuba down to 61.
"The United States is grateful to the government of the United Arab Emirates for its humanitarian gesture and willingness to support ongoing US efforts to close Guantanamo," the Pentagon said in a statement.
Since the September 11, 2001 attacks in New York, about 780 inmates have been kept at Guantanamo.
Once freed, former prisoners are usually subject to supervision and what are called rehabilitation programs.
Amnesty International USA, a rights group, welcomed the announcement as a sign US President Barack Obama was serious about closing the controversial jail before he leaves office.
"It's a significant repudiation of the idea that Guantanamo is going to be open for business for the indefinite future," Naureen Shah, Amnesty International USA's security and human rights program director, told the AFP news agency.
US accelerates releases
One of those transferred was an Afghan called Obaidullah, who was allegedly to have planted land mines in 2001. He was held for 14 years without trial.
Obama wants to close the facility before he leaves office at the start of next year but has been continually opposed by Republican lawmakers.
Still, the US has in recent months accelerated the rate at which prisoners who have been approved for transfer are released from the jail.
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"We expect every single one of them to be released before [Obama] is out of office," Shelby Sullivan-Bennis, a lawyer at Reprieve US who represents Mohsen Aboassy, one of the released prisoners told Al Jazeera.
"The processes that the administration is putting in place are rapidly happening over the next five months or so before the administration moves out. We are happy to say that we expect all of them to be transferred out."
When Obama took office there were 242 detainees at Guantanamo. Monday's announcement means 19 inmates remain who have already been cleared for transfer.
Donald Trump's vow
November's presidential election will likely help determine the future of the prison, as Republican presidential candidate Donald Trump has vowed to fill Guantanamo with "bad dudes" should he win the White House.
Trump has said he would "bring back a hell of a lot worse than waterboarding," referring to a method of torture banned by the US government in 2007.
READ MORE: Trump to form committee 'on radical Islam' if president
To date, just 10 of the prisoners have faced a criminal trial, including the "9/11 Five" led by Khalid Sheikh Mohammed who were accused of plotting the September 11, 2001 attacks.
Guantanamo is a US naval base carved out of a remote chunk of land on the tip of southeastern Cuba. The government of George W Bush opened the prison there.
Source: Al Jazeera and agencies