But while the facility in southeastern Cuba and the 40 inmates who remain there are not budging, the staff doesn't stay put for long.

A continually changing roster of senior leaders -- 18 generals and admirals -- have rotated through the military prison, which first opened in January 2002 in the wake of the September 11, 2001 attacks.

And the 1,800 troops who guard the prisoners tend to do stints of six to nine months.

The brief deployments and constant changes mean institutional knowledge of Guantanamo has suffered, said Navy Admiral John Ring, who currently heads prison operations.

"One of the problems that we have is the lack of continuity (of staff). So we are doing some things about that," Ring told reporters on a recent media tour.

He said he had just hired a civilian deputy and some civilian assistants, who can stay for longer than military personnel.

"We definitely desire to have people down here longer," he says.

"One of the challenges we have on that is that the base doesn't have enough family housing," Ring adds, noting that problem could take years to resolve.

Critics are concerned that the constant rotation of prison guards risks further isolating the inmates, some of whom have still not been charged despite 16 years in detention.

Ring said the Pentagon had recently sent a memo to the prison, telling leaders to plan to remain open for at least 25 more years -- meaning new solutions must be found.

- Limited therapy time -

Among those with the shortest rotations at Guantanamo are the three psychiatrists tasked with keeping tabs on prisoners.

Some inmates are in legal limbo awaiting movement in their cases, which are often bogged down in red tape in special military tribunals.

"On a typical week, we see two to three people probably," says one psychiatrist who, like all those with prisoner contact, wears no identification on his uniform for security reasons.

"The vast majority of people are dealing with issues that the regular population that are detained deal with. I am just trying to keep motivation, things like that, trying to keep their heads up."

Since the prison opened, nine detainees have died, including seven who committed suicide. One prisoner died of cancer, and another of a heart attack.

Talk therapy is especially limited after the American Psychological Association barred its members from treating detainees at Guantanamo, saying they should not work in facilities that do not comply with human rights laws.

So much of the psychiatrists' work is based on prescribing drugs.

Like the doctors, the guards do not do long deployments because, according to Ring, "it's perhaps not a good thing" for them to have prolonged contact with prisoners.

The inmates are "master manipulators," he says.

But Guantanamo critics say a lack of meaningful contact between the guards and the prisoners risks stripping the jailors of any feeling of responsibility and dehumanizing the inmates -- a violation of the Geneva Conventions on humanitarian treatment of detainees.

The main form of continuity at Guantanamo is a man, aged about 50, who gives his name as "Zaki."

Since September 2005, he has served as a "cultural advisor" at Guantanamo, advising military cooks how to prepare halal dishes for prisoners, and instructing guards on how to respect the inmates' need to pray and other cultural differences.

Yet, while he speaks Arabic, Zaki's interaction with prisoners is very limited: he says he has not spoken to a single prisoner for a year.

Ring acknowledged that his own institutional knowledge of the prison sometimes falls short.

When asked what year the harsh interrogation practices likened to torture ended (officially in 2004), he says: "I was not here. I don't know all the details."

"I have been here only for a year," Ring added.