he road to Abu Ghraib began, in some ways, in 2002 at Guantánamo Bay. It was there that the Bush administration began building up a worldwide military detention system, deliberately located on bases outside American soil and sheltered from public visibility and judicial review. The administration shunned the scrutiny of independent rights monitors like Human Rights Watch and Amnesty International. It presumed that suspected agents of terrorism did not deserve normal legal protections, and it presumed that American officials could always tell a terrorist from an innocent bystander.

So far as we know, the psycho-sexual humiliations that military jailers inflicted on Iraqi detainees last year at Abu Ghraib have no parallels in American-run prisons elsewhere. Nevertheless, accounts from former prisoners at other military detention sites — including smaller holding centers in Iraq, the main Afghan prison at Bagram Air Base near Kabul, and Guantánamo itself — suggest there has been systemic, gratuitous brutality against people who in many cases are not clearly guilty of any crimes. In one chilling indication of the extent of the problem, the Pentagon said this week that 25 Iraqi and Afghan war detainees had died in American custody in the past 17 months.

The interrogation and detention methods that the Pentagon acknowledges having regularly used include forms of physical and psychological abuse that violate American values, international standards of human dignity and the lawful rules of war. These include sleep deprivation and forcing prisoners' bodies into "stress positions" for hours at a time. Until recently, detainees were commonly interrogated with hoods over their heads. Stripping them naked was permitted so long as a general signed off on the request. Judging from the photos, that wasn't much of a barrier.

Accounts of sickening abuses have been published in the pages of this and other newspapers for months, largely based on the testimony of detainees who were ultimately found to pose no threat and were released. Reputable international human rights groups have issued reports pointing to unacceptable treatment of detainees.

President Bush said he had been kept in the dark about the pictures of the Abu Ghraib abuse until they were broadcast on CBS last week. But if Mr. Bush was unaware, it was only of the fact that there were pictures. We now know that that he and senior administration officials were told months ago of concerns about the severe mistreatment of detainees in Iraq. The administration has shown little interest in addressing these problems, and there has been little political will elsewhere to pressure the Pentagon to clean up its act. That must now change.

In Iraq, as we now know, hooded detainees have been beaten, stripped naked, fitted with animal leashes and forced into degrading sexual positions. More than a year ago, released detainees from Bagram told Carlotta Gall of The Times that they had been made to stand naked for hours at a time, with hoods over their heads, their feet shackled and their arms chained to the ceiling. They also reported that bound Muslim male prisoners had been kicked and humiliated by female prison guards. Other released prisoners complained to Human Rights Watch of being made to stand motionless for hours on end before interrogations, with bright spotlights shining into their eyes. Some, though not all, of their charges were explicitly denied by American military officials.

Less is known about the detention and interrogation conditions at Guantánamo, but complaints have been made about abuses there as well. Many of the allegations made by people released from America's various military detention centers have been treated skeptically in the past. Now they all deserve careful investigation.

It is troubling that the worst abuses at Abu Ghraib apparently occurred after Maj. Gen. Geoffrey Miller, then in charge of the Guantánamo detention center, recommended changes in interrogation procedures for detainees in Iraq. General Miller is the same official the Bush administration has now put in charge of detentions and interrogations in Iraq.

Despite its best efforts, the government has never been able to demonstrate any strong link between Iraq and Al Qaeda before the invasion. But since then, Iraqi prisoners have been treated like suspected terrorists. The abuses in Abu Ghraib and throughout the military detention system stain this country's reputation and play into Osama bin Laden's portrait of an evil America. The Bush administration has given a gift to Al Qaeda's worldwide recruitment efforts.