As journalists passed along a darkened corridor at the Guantanamo Bay lockup, a detainee displayed a hand-painted sign through the one-way glass of his cellblock: A white question mark against a blue background, the dot in the shape of a padlock.

The prisoner has good reason to be uncertain.

President Barack Obama pledged to close the offshore detention center upon taking office, but as time runs out on his administration that almost certainly will not happen. More than half the men still held here have not been cleared for release and Congress has prohibited moving prisoners to the U.S. for any reason. The prison's future will then be up to President-elect Donald Trump, who has said he would prefer to keep it open and even "load it up with some bad dudes."

It puts the military in an awkward situation.

"At this point, we are continuing to do our job in supporting the president in his efforts to close the detention facility," said a prison spokesman, Navy Capt. John Filostrat.

But officials at the base also readily concede they have available cells and could expand if needed if the new administration so desires.

"We are prepared to continue detention operations in the same professional manner that we do today," the detention center commander, Navy Rear Adm. Peter Clarke, told journalists at the end of a recent tour.

The U.S. opened Guantanamo to hold militants suspected of ties to al-Qaida and Taliban in the aftermath of the terror attack of Sept. 11, 2001. Most were never charged with a crime, and the indefinite detention, combined with the mistreatment of prisoners in the early days of the detention center, prompted global criticism. Earlier this month, Obama called it a "blot on our national honor."

There are now 59 prisoners at Guantanamo, down from 242 when Obama took office and a peak of nearly 680 in July 2003. Of those who remain, 22 are cleared for release and some are expected to be transferred out in the final weeks of the administration. Congress has barred moving them to facilities in the United States for any reason, including trial, so they are otherwise stuck at the base.

The military has consolidated the prisoners who are left into two units and has not replaced nearly 300 American troops who recently left. Large sections of the detention center are now vacant amid the rolling, cactus covered hills of southeastern Cuba.

But there are also signs that the detention center isn't going away soon. The military is building a medical clinic, at a cost of $8.4 million, inside a recently vacated prison unit to eliminate the need to transport detainees to the base's existing one. The government is also building a $12.4 million dining facility for troops who work at the prison and seeking the funds for better housing.

And the military tribunals for seven detainees who have been charged with war crimes, including five men accused of planning and aiding the 9/11 attack, have been slogging along in the pretrial stage for years and no trial dates have even been scheduled.

Fifteen "high-value" detainees, including the Sept. 11 defendants, are held in Camp 7, a maximum-security unit that the military does not show to journalists. Even its exact location on the base is classified.

All the other detainees are now in Camp 6, a glass and concrete prison facility where they live in air-conditioned communal pods, allowed to roam free of their cells 22 hours a day. The men eat and pray together, play soccer, attend art and language classes, and have access to movies and satellite TV, which officials say allowed them to closely follow the U.S. election.

The men there include Khalid Qasim, whose lawyer identified him as the man who held up the question mark painting. A review board determined in 2015 that he had trained with al-Qaida in Afghanistan and should not be released, though the U.S. has no intention of prosecuting the 39-year-old from Yemen.

"His 14-plus years of detention, without charge or trial, are an affront to U.S. values," said his lawyer, Shelby Sullivan-Bennis of the human rights group Reprieve. "All Khalid wants is to be reunited with his family, and to rebuild his life. Obama must urgently grant him his freedom, before it's too late."

Sullivan-Bennis said that whenever she visits, her client asks why he is still there or why can't he have a trial. She said he has chosen to express his "Kafka-esque plight" though his art.

The jail's commander says he can't say what will happen to Qasim or any of the other prisoners.

"You know the detainees have questions of whether the transfers are going to stop when the new president takes charge Jan. 20," Clarke said. "We don't know, they don't know. Their lawyers may speculate, but no one knows. "