GUANTANAMO BAY NAVAL BASE, Cuba â€"  The U.S. has finally started the prosecution of five Guantanamo Bay prisoners charged in the Sept. 11 attacks that killed nearly 3,000 people, but the trial won't be starting anytime soon, and both sides said Sunday that the case could continue for years.

Defense lawyer James Connell said a tentative trial date of May 2013 is a "placeholder" until a true date can be set for the trial of Khalid Sheikh Mohammed, the self-described mastermind of the attacks, and his co-defendants.

"It's going to take time," said the chief prosecutor, Army Brig. Gen. Mark Martins, who said he expects to battle a barrage of defense motions before the case goes to trial.

"I am getting ready for hundreds of motions because we want them to shoot everything they can shoot at us," he said.

Saturday's arraignment lasted 13 hours, including meal and prayer breaks, as the accused appeared to make a concerted effort to stall the initial hearing, which didn't end until almost 11 p.m.

"Everyone is frustrated by the delay," Martins said on Sunday. He noted that the civilian trial of convicted Sept. 11 conspirator Zacarias Moussaoui took four years, and he pleaded guilty in 2006 before being sentenced to life in prison.

On Saturday, Mohammed and his co-defendants refused to respond to the judge or use the court's translation system and one of the men demanded a lengthy reading of the charges. Connell called the tactics "peaceful resistance to an unjust system."

The arraignment, Connell said, "demonstrates that this will be a long, hard-fought but peaceful struggle against secrecy, torture and the misguided institution of the military commissions."

The defendants' actions outraged relatives of the victims.

"They're engaging in jihad in a courtroom," said Debra Burlingame, whose brother, Charles, was the pilot of the plane that flew into the Pentagon. She watched the proceeding from Brooklyn on one of the closed-circuit video feeds around the United States.

A handful of those who lost family members in the attacks were selected by a lottery and flown to watch the proceedings at the U.S. naval base in Cuba, where Mohammed and his co-defendants put off their pleas until a later date.

They face 2,976 counts of murder and terrorism in the 2001 attacks that sent hijacked jetliners into New York's World Trade Center and the Pentagon. The charges carry the death penalty.

The detainees' lawyers spent hours questioning the judge, Army Col. James Pohl, about his qualifications to hear the case and suggested their clients were being mistreated at the hearing, in a strategy that could pave the way for future appeals. Mohammed was subjected to a strip search and "inflammatory and unnecessary" treatment before court, said his attorney, David Nevin.

It was the defendants' first appearance in more than three years after stalled efforts to try them for the terror attacks.

The Obama administration renewed plans to try the men at Guantanamo Bay after a bid to try the men in New York City blocks from the trade center site hit political opposition. Officials adopted new rules with Congress that forbade testimony obtained through torture or cruel treatment, and they now say that defendants could be tried as fairly here as in a civilian court.

Nevin said it would be impossible to present testimony against his client that wasn't corrupted by treatment that he says amounted torture. "It's not possible to untaint the evidence any more than it is to unring a bell."

Eddie Bracken of Staten Island, New York, was one of the victims' relatives allowed to attend the hearing, and said it was important to him to see the people accused of killing his sister, Lucy Fishman, a Brooklyn mother of two who worked in the World Trade Center.

He said he came away impressed by the military justice system, with defense lawyers putting up an aggressive defense.

"If they had done this in another country it would have been a different story," Bracken said Sunday. "But this is America."

Human rights groups and defense lawyers say the secrecy of Guantanamo and the military tribunals will make it impossible for the defense. They argued the U.S. kept the case out of civilian court to prevent disclosure of the treatment of prisoners like Mohammed, who was waterboarded 183 times.

Attorney General Eric Holder announced in 2009 that Mohammed and his co-defendants would be tried blocks from the site of the destroyed trade center in downtown Manhattan, but the plan was shelved after New York officials cited huge costs to secure the neighborhood and family opposition to trying the suspects in the U.S.

Congress then blocked the transfer of any prisoners from Guantanamo to the U.S., forcing the Obama administration to refile the charges under a reformed military commission system.

Mohammed, a Pakistani citizen who grew up in Kuwait and attended college in Greensboro, North Carolina, has admitted to military authorities that he was responsible for the Sept. 11 attacks "from A to Z," as well as about 30 other plots, and that he personally killed Wall Street Journal reporter Daniel Pearl. Mohammed was captured in 2003 in Pakistan.

Ramzi Binalshibh was allegedly chosen to be a hijacker but couldn't get a U.S. visa and ended up providing assistance such as finding flight schools. Walid bin Attash, also from Yemen, allegedly ran an al-Qaida training camp in Afghanistan and researched flight simulators and timetables. Mustafa Ahmad al-Hawsawi is a Saudi accused of helping the hijackers with money, Western clothing, traveler's checks and credit cards. Ali Abd al-Aziz Ali, a Pakistani national and nephew of Mohammed, allegedly provided money to the hijackers.

During the failed first effort to prosecute the men at the base in Cuba, Mohammed mocked the tribunal and said he and his co-defendants would plead guilty and welcome execution. The lawyers' statements indicate that plan has changed.