New York City - Time moves slowly for the five men accused of the 9/11 attacks.

Sixteen years after the World Trade Center was toppled, the case against the alleged mastermind and his co-plotters looks set to drag on for years, if not decades, defence lawyers told Al Jazeera.

Apart from Hurricane Irma's 250kph winds, little moves fast at Guantanamo Bay, the US Navy base in southeast Cuba where the men are detained. Their proceedings have not picked up pace since Donald Trump became president of the United States in January.

Khalid Sheikh Mohammed, or "KSM", has been dubbed the "architect of 9/11". He and his four alleged co-conspirators all face the death penalty in a case that is still crawling through the pretrial stages of a military commission.

"It perplexes me that this isn't a cause for more outrage back in the US," Shayana Kadidal, a lawyer on several post-9/11 cases for the Center for Constitutional Rights legal action group, told Al Jazeera.

"According to the government, you have the person by far most responsible for planning 9/11 and a couple of people just below him responsible for executing the plot. They've been sitting in detention for the most part of 14 years, without trial, and, by all appearances, any trial is years and years off."

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At a hearing in August, prosecutors mooted an early 2019 trial start date, saying it would take between six and eight weeks to lay out evidence that the men planned and aided the hijacking of four passenger jets on September 11, 2001.

They would be tried on the 117-square-kilometre base, popularly known as Gitmo, on charges of "terrorism" and some 3,000 counts of murder in violation of the law of war. They could face execution if convicted by a jury of military officers.

They were arraigned in 2012, but the case has become bogged down in pretrial motions as defence lawyers claimed they were bugged and spied on and requested classified evidence of torture-like treatment in CIA custody.

"There're so many obstacles to trial that I'm not sure they'll ever get there," Nancy Hollander, a lawyer in a separate Guantanamo case, told Al Jazeera.

Should the men ultimately be convicted, appeals would likely drag on for years longer before reaching the US Supreme Court, she said.

"Let's say by some miracle they're found not guilty, they're not going home," added Hollander. "These are show trials and bad show trials at that."

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KSM allegedly hatched the 9/11 plot, secured al-Qaeda boss Osama bin Laden's support, and oversaw operations and trained hijackers in Afghanistan and Pakistan.

The other men - Walid bin Attash, Ramzi bin al-Shibh, Ammar al-Baluchi and Mustafa al-Hawsawi - allegedly trained hijackers, arranged travel and flight school courses or wired money to fund the attacks on New York and Washington, DC.

The evidence against KSM is strong, said Kadidal, not least because he bragged to Al Jazeera journalist Yosri Fouda about his involvement in 2002 - before he was arrested by Pakistani authorities in Rawalpindi in March 2003.

But prosecutors have problems too. KSM was waterboarded 183 times in a single month and endured sleep deprivation and "rectal rehydration", according to a Senate report on CIA torture techniques. This provides ammunition for his defence team.

The accused men were originally arraigned in 2008, but those charges were suspended when former President Barack Obama, a Democrat, opted for civilian trials in New York. That plan was blocked by legislators amid outrage from victims' families.

Many people say justice is taking too long. Joel Shapiro, whose wife died in the attacks, has called for dropping the death penalty and cutting plea deals with the accused. Terry Strada, who lost her husband and runs a group for 9/11 families, disagrees.

"I know it's been a very long time and some family members are upset," Strada told Al Jazeera. "They're doing everything in their power to ensure that no mistakes are made, and there's no opportunity for them to have a mistrial and elude the guilty verdicts they deserve."

On Monday, Strada will attend a private service at the start of a day of vigils across the US, as well as the televised reading of victims' names at a four-hour ceremony in lower Manhattan where the Twin Towers once stood.

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Opened in 2002 as a makeshift camp to hold men captured in the early fight against al-Qaeda, Guantanamo became a symbol of Washington's heavy-handed response to 9/11. It held some 680 men at its peak in July 2003, falling to nearly 240 when Obama took office in 2009.

Obama never made good on campaign pledges to shutter Guantanamo, but a flurry of transfer deals with Saudi Arabia, Oman, and other countries at the end of his presidency brought the detainee population down to 41.

Advocates say it keeps killers behind bars. Critics say it violates rights by holding men indefinitely without charge, that it feeds anti-US sentiment abroad, and that detainees could be held more cheaply in jails on the US mainland.

During the campaign, Trump, a Republican, promised to "load it up" with more "bad dudes". An executive order, drafted in February but not issued, called for Guantanamo to house captured fighters from the Islamic State of Iraq and the Levant group (ISIL).

Trump may have the popular mood: a CNN/ORC poll last year found that 56 percent of Americans wanted Guantanamo kept open. Last month, secretary of state Rex Tillerson announced plans to remove the envoy responsible for shuttering it.

White House Chief of Staff General John Kelly, whose son was killed fighting in Afghanistan, has argued to keep it open. Attorney General Jeff Sessions called it "a very fine place" to interrogate and prosecute "terrorism" suspects.

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However, after al-Qaeda suspect Ali Charaf Damache was extradited to the US from Spain in July, he was sent for trial at a Philadelphia federal court rather than Guantanamo. This was likely a condition of the Spanish courts, said Hollander.

Karen Greenberg, who runs Fordham University's Center on National Security, said the Trump administration's signals suggest the "future of anybody who's at Guantanamo Bay is as much in limbo as it's ever been".

Besides KSM and his co-accused, two other men face military commissions. The inmates also include five men who have been cleared for release and 26 so-called "forever prisoners" who are held indefinitely without charge.

"The American public has forgotten about Guantanamo. History in this country is short," said Hollander.

"Do most Americans care about Guantanamo? No. But they never did. And they never understood Guantanamo."

Follow James Reinl on Twitter: @jamesreinl