President Bush, Secretary of Defense Donald Rumsfeld and a bipartisan chorus in Congress are rightfully appalled by the images from last fall of U.S. soldiers abusing their Iraqi prisoners at the infamous Abu Ghraib prison.

The disturbing photos showed naked prisoners. They'd been forced into degrading postures by their U.S. captors. Some of the photos suggest sexual abuse.

Rumsfeld said such actions were "unAmerican," and was dismayed that the photos appeared late last week on the CBS news program "60 Minutes" before the military saw them.

Indeed, it is unAmerican, and it cannot be stated strongly enough that we've no doubt that it does not represent either the actions nor the attitude of most American military personnel serving in Iraq and around the world.

But just as good cops need to rid themselves of the bad ones in their ranks, we — and especially our allies — need to be confident that that there is no systemic problem here. So far, seven soldiers face military discipline. More investigations could bring more action and more answers.

Yet Rumsfeld already is trying to downplay the incident as isolated. He said that the abuse at Abu Ghraib prison was "not a pattern or a practice" found elsewhere.

Rumsfeld has used that same phrase, "pattern or practice," before. When two British citizens who'd been held at the prison on Guantanamo Bay on suspicion of terrorism were released in March, they said they had been beaten and had endured psychological torture.

Rumsfeld's reply: "It is a pattern and a practice of terrorists to allege abuse. We've seen that in their training."

This kind of off-handed dismissal isn't going to work when the administration itself has drawn the war-on-terror zone so broadly.

This go-anywhere, do-anything war has been cited as justification for the indefinite detention of suspected enemies, without trial or counsel.

It wasn't too long ago that some military personnel seriously discussed the merits of using torture on suspected terrorists in extreme cases.

So who is to say the soldiers who abused their prisoners didn't simply figure that all is indeed fair in this war on terror — including the abuse of their prisoners?

Deft denials won't work now. What will work is a thorough investigation, with no attempt to either scapegoat or excuse. Only that will restore the world's faith in U.S.justice and fairness.