A recent report by Amnesty International likened the facility, located at a U.S. Navy base on Cuba, to a modern "gulag." But the administration of U.S. President George W. Bush is strongly defending the need to keep it open.
More than 500 suspected terrorists from 40 countries are held at Guantanamo -- some for more than three years. Only four have been formally charged with a crime.
Yesterday, U.S. Defense Secretary Donald Rumsfeld argued that Guantanamo remains a key part of the U.S. war on terrorism despite alleged abuses of detainees. The Pentagon has confirmed cases of mishandling the Koran at Guantanamo, an issue that has sparked protests across the Muslim world.
Rumsfeld told a news conference in Washington that no detention facility in the history of warfare has been more transparent or received more scrutiny.
"The U.S. military has also gone to unprecedented lengths to respect the religious sensibilities of these enemies of civil society, including the issuance of detailed regulations governing the handling of the Koran and arranging schedules for detainees around the five daily calls for prayer required by the Muslim faith," Rumsfeld said.
Rumsfeld's remarks came after U.S. Vice President Dick Cheney declared on 13 June that there are no plans to close the camp. Cheney rejected criticism from U.S. lawmakers and rights groups who say the alleged abuses there are hurting America's image abroad.
"Does this hurt us from the standpoint of international opinion? I frankly don't think so," Cheney said.
But Senator Patrick Leahy, a Democrat from the state of Vermont, disagrees. Leahy said in the Senate on 13 June that Guantanamo is "a national disgrace" and an international embarrassment" to the United States as well as "a festering threat" to U.S. security.
"[The stain of] Guantanamo has become the primary recruiting tool for our enemies," Leahy said.
The debate in Washington centers on allegations that U.S. forces have abused detainees in an overzealous effort to get information that might prevent future terrorist attacks.
Leahy says the Bush administration has not lived up to its promise to treat detainees humanely. He says the administration has blocked any independent investigation into the alleged mistreatment of detainees.
Arizona Republican Senator John McCain says there is no doubt that allegations of abuse and torture at Guantanamo have created an image problem for the United States.
McCain rejects the idea of closing the facility. But he says the judicial process should be moved forward so that detainees are brought to trial for any crime they are accused of rather than being held indefinitely.
Duncan Hunter, a Republican congressman from California, supports the administration's efforts to convince the public that detainees are well treated. Hunter recently showed journalists samples of food for the detainees that respects Islamic beliefs.
"This is lemon fish. And this is what the 20th hijacker [of the September 11th attacks] and Osama bin Laden's bodyguards will be eating this week in Guantanamo," Hunter said.
Cheney has suggested that calls for closing Guantanamo are politically motivated:
"Those who are most urgently advocating that we shut down Guantanamo probably don't agree with our policies anyway," Cheney said.
But as the debate heats up, some prominent Republicans also are beginning to question the need to keep Guantanamo open.
Among them is Florida Senator Mel Martinez, who was a member of Bush's first cabinet and is now on the Senate Foreign Relations Committee.
On 10 June, Martinez described Guantanamo as "an icon for bad stories" and said the administration should consider closing it.
Senator Joseph Biden, the highest-ranking Democrat on the Foreign Relations Committee, has led the calls among legislators for the closure of Guantanamo.
"I think we should end up shutting it down, moving those prisoners. Those who we have reason to keep, keep. Those we don't, let go. But the bottom line is I think more Americans are in jeopardy as a consequence of the perception that exists worldwide with its existence than if there were no [Guantanamo]," Biden said.
Sam Zarifi, a researcher for Human Rights Watch, tells RFE/RL that the Bush administration needs to be more transparent about how suspected terrorists are interrogated -- not only at Guantanamo, but also at detention centers run by the U.S. military in Iraq and Afghanistan.
"Among the more important things in the immediate term are making sure that prisons are subject to international law. To the issue of prisoner abuse, it's really time for President Bush to look for real accountability -- including the highest levels of his own government," Zarifi said.
Last week's report by Amnesty International said all detention centers run by the U.S. military need to be independently investigated. Amnesty also has accused the Bush administration of "thumbing its nose at the rule of law and human rights."
President Bush has dismissed the criticisms by Amnesty International, describing the report as "absurd."