Guantanamo Bay detainees are staging suicide attempts and hunger strikes to undermine American policy in the war on terror, a senior U.S. military official said, calling the acts a "jihad" against the United States.

"The detainees view this as a struggle. They view this as a jihad ... They're trying to figure out ways that they can continue the fight," Navy Rear Adm. Harry Harris, the commander of the U.S. prison on Cuba's southeastern tip. "They do that with hunger strikes, overdosing on medicines. And now they've succeeded in killing themselves."

Three detainees — two Saudis and a Yemeni — committed suicide in their cells on June 10. The U.S. military said the men hanged themselves by fashioning nooses from bed sheets. Harris said the deaths and other suicide attempts were coordinated acts of resistance — not acts of desperation prompted by their indefinite detention.

"I think it is less about the length of their detention ... It's less about that and it's more that they continue to fight their fight," Harris told reporters, adding that defiance in the prison was widespread. "I think the vast majority of detainees are resisting us."

President Bush has said he wants to close the detention center but is seeking guidance from the nation's top court on the matter. The U.S. Supreme Court could rule as early as Wednesday on the legitimacy of military tribunals ordered by Bush, the first such trials since World War II.

Harris, who took over command at Guantanamo on March 31, said he believed a ruling by the court wouldn't affect operations at the prison, which he said served a vital role in the U.S.-led war on terror.

"Given the battle that we're fighting as a nation, I believe there is a need for places like Guantanamo," Harris said.

The suicides of the three detainees prompted renewed calls from European countries and human rights groups to close Guantanamo, which holds about 450 men on suspicion of links to al-Qaida or the Taliban.

A spokesman for Boston-based Physicians for Human Rights said that whether the suicides were a political act or the product of desperation does not change "the fact that U.S. detention and interrogation practices have violated basic tenets" of the Geneva Conventions and the McCain Amendment, which prohibits torture or cruel, inhuman or degrading treatment of prisoners.

"Regardless of the motivation that caused the three detainees at Guantanamo to commit suicide, those being held without charge are still entitled to due process and to receive treatment that is in accordance with basic human rights standards," said spokesman Nathaniel A. Raymond from Boston.

A military doctor at the prison said the three detainees received psychological exams only days prior to their suicides and showed no signs of being depressed. He spoke on condition of anonymity to protect his personal safety.

The doctor suggested the exams, performed by mental health professionals one to two weeks before the suicides, supported assertions by military officials that the prisoners killed themselves as a political act — not because they were despondent about their prolonged detention.

"None had showed any signs of being depressed or having a mental condition," said the doctor, who is the medical officer in charge of the prison. He said medical personnel examined the detainees some 10 minutes after they were found and "did everything we could" to revive them, including using defibrillators.

Since the deaths, the military has implemented strict measures to guard against future suicides, including only giving out bed sheets and blankets during sleeping hours and monitoring detainees in their cells every three minutes.

Officials have also lowered the threshold to determine when a detainee is at risk of being suicidal, the doctor said. Now, any detainee thought to be a suicide risk is placed in a tear-proof anti-suicide smock — which can't be fashioned into a makeshift noose — for 72 hours and given a psychological exam, he said.

There are currently about 20 detainees in green anti-suicide smocks, the doctor said.

The doctor said there have been no suicide attempts since the June 10 suicides, but there have been several incidents of detainees harming themselves, such as cutting themselves with paint chips or beating their heads against walls.