US officials have announced the first charges against foreign detainees at Guantanamo Bay in Cuba.
Two men, who the US says are members of the al-Qaeda network, face charges of conspiracy to commit war crimes. BBC News Online looks at their legal status.
Who are these two men? Why are they the first to be charged?
According to the charge sheets, the two men were bodyguards of Osama Bin Laden, as well as performing a number of other activities for the al-Qaeda network.
Ali Hamza Ahmed Sulayman al-Bahlul is alleged to have been a member of al-Qaeda since 1999, Ibrahim Ahmed Mahmoud al-Qosi since 1989.
Most of the detainees have been held for more than two years
Pentagon officials suggest these two are the first to be charged because the cases against them are the most advanced - not that they are necessarily the most dangerous suspects held by the Americans.
How detailed are the charges?
The charge sheets against the two are each about four pages long. Both include general allegations against al-Qaeda.
Both men are accused of conspiring, among other things, to attack civilians and destroy property, and commit acts of terrorism. Both are said to have undertaken al-Qaeda military training in Afghanistan.
And, as well as acting as bodyguards and helping Osama Bin Laden, Mr Bahlul is accused of being a key propagandist - including making a video glorifying attacks on Americans, like the bombing of the USS Cole, to help with recruitment.
Mr Qosi is accused of being an accountant who helped with the finance of al-Qaeda operations, and acting as a weapons smuggler.
How much do we know about military tribunals?
The military commissions will be before military judges, with military prosecutors and defenders.
The Pentagon says the treatment of the detainees is consistent with international laws of war. It says it has tried to make the process fair, that defendants will be able to consult civilian lawyers, and that there will be media coverage, so they will not be secret.
About 650 still detained
87 detainees released unconditionally
5 released into continued detention: 4 Saudi and 1 Spanish
9 UK detainees: 5 to be released and repatriated
2 Australian detainees: Families campaigning for release, but Australian Government does not want them repatriated
1 Danish detainee to be released
Other aspects of the tribunals:
Defence lawyers are military officers chosen by the Pentagon
Some aspects of the trial might be held in secret and defendants may not hear all the evidence against them
Appeals against the tribunal's rulings are possible, but before another panel of military judges
Even if a suspect is acquitted, he may continue to be held for security reasons.
Critics say the process is unfair and that there is not sufficient independent oversight, especially over an appeals process.
Leading human rights groups say that the Pentagon has turned down their request to observe the military tribunal trials of detainees at Guantanamo Bay, because there is not enough courtroom space.
President George W Bush announced in December 2003 that civilian review panels would be set up to scrutinise the findings of the military tribunals. The Department of Defense has also said that a panel will annually review the status of inmates who are not charged.
What is the US Supreme Court's view of all this?
The Supreme Court is due to hear two Guantanamo related cases this year.
The first challenges the US Government's claim that US civilian courts have no jurisdiction over those held at Guantanamo Bay.
The second is being brought on behalf of an American citizen of Saudi Arabian descent who has been held in a military prison since his capture.
Rulings are expected this summer, but the current Supreme Court has a conservative leaning and the court has tended to steer clear of military matters it considers the business of the executive and the Department of Defense.
What happens to those found guilty?
Those found guilty by military tribunals will be sentenced by military judges. If there are any criminal trials, they will be sentenced in the ordinary manner.
Depending on the particular charges, the death penalty may be available. Pentagon officials say that in the case of the two now charged, they will not be seeking the death penalty.
There is an appeals process, but for the moment it is within the official Pentagon and administration structure. This is one of the issues being contested in cases before, among others, the Supreme Court.
Why are the detainees in Cuba?
In the aftermath of the war in Afghanistan in 2001, about 660 people from 42 countries were sent to Guantanamo Bay for interrogation and detention.
The detainees were taken to a place outside US territory to minimise the application of legal constraints that might otherwise apply.
The US has an indefinite lease on Guantanamo Bay as a base from a Cuban government which preceded that of Fidel Castro.
What is their status?
The Bush administration considers them to be "enemy combatants", but unlawful ones, outside the normal legal framework. Aside from two men who have now been charged, they are being held indefinitely without trial or access to lawyers.
The concept of "unlawful combatants" comes from a case during World War II in which German saboteurs were caught in the US wearing civilian clothes.
The US courts held that they were not subject to the protection of the Geneva conventions, which say that civilians can become combatants but must carry arms openly and respect the rules of war. Several saboteurs were executed.
Washington says it will not treat the detainees as normal criminals because of their alleged links to Osama Bin Laden's al-Qaeda network.
What does their status mean for the detainees?
If the detainees are not legally prisoners of war, then they are not entitled to various protections provided by the Geneva conventions.
Also, certain restrictions on interrogation of prisoners-of-war, contained in the Geneva conventions, do not apply.