The US government has approved the release of five more prisoners from the Guantanamo Bay military prison, according to documents posted online this week by the Defense Department.

Three of the five detainees were from Yemen, one was from Somalia, and the fifth from Kenya. 

They have spent a collective 85 years in the prison opened two decades ago for so-called "war on terror" detainees in the wake of the September 11, 2001 Al Qaeda attack on the United States.

Never charged, detainees now approved for release -- decided after case reviews in November and December -- total 18 of the 39 men still held in the prison facility at the US Naval Base in Cuba.

Those newly approved for release are Somali Guleed Hassan Ahmed (also called Guled Hassan Duran); Kenyan Mohammed Abdul Malik Bajabu; and Omar Muhammad Ali al-Rammah, Moath Hamza al-Alwi, and Suhayl al-Sharabi of Yemen.

The Pentagon's Periodic Review Board found that all did not present, or no longer presented, a threat to the United States.

But like the others approved, their releases could be delayed as Washington seeks arrangements with their own or other countries to accept them.

Repatriation challenge 

Currently the United States will not repatriate Yemenis due to the civil war in the country, or Somalis, whose homeland is also mired by domestic conflict.

The release approvals indicated an accelerated effort by the administration of President Joe Biden to resolve the situations of the 39 in Guantanamo, after his predecessor Donald Trump effectively froze action.

Tuesday marked the 20th anniversary of the opening of the Guantanamo prison, and brought calls from international human rights groups to shut it down, accusing the United States of arbitrary detention of hundreds of people and the illegal torture of dozens.

On Monday a group of UN human rights experts called for Washington to "close this ugly chapter of unrelenting human rights violations."

Writing on the Lawfare website, US Senator Dianne Feinstein said those detainees facing trial, including September 11th mastermind Khalid Sheikh Mohammed, could be tried in US civilian courts rather than the secretive and troubled military commissions system.

"Now that the US's war in Afghanistan is over, it's time to shut the doors on Guantanamo once and for all," Feinstein said.

Mental health 

Of the 39 men still at Guantanamo, 10 are in the process of standing trial, mostly still in preliminary proceedings; two have pleaded guilty to terror-related charges; and nine remain in limbo, neither charged nor yet granted release.

Some of the nine, Guantanamo defense attorneys say, have mental health problems that make it hard to present a case for release to the boards or arrange a future life in their home countries or elsewhere.

Khalid Ahmed Qasim, whose case was reviewed in December, was denied release even though the Pentagon authorities in charge of the reviews acknowledged that he was not a significant person in Al-Qaeda or the Taliban and did not pose a significant threat.

But they indicated that he frequently would not comply with officials at the Guantanamo prison and lacked plans for his future if he was released.

The board "encourages the detainee to immediately work toward showing improved compliance and better management of his emotions," it said.

It asked his attorneys to produce a plan "regarding how his mental health conditions will be managed if he were to be transferred" out of Guantanamo.