Who is really to blame for the cruel and disgusting incidents recounted in the trial of Sgt. Michael J. Smith, 24, of Boynton Beach, Fla., the dog handler convicted by a military jury of abusing detainees at Abu Ghraib prison in Iraq?

Photographs that surfaced in late 2003 showed naked prisoners stacked

in human pyramids and U.S. soldiers posed alongside other prisoners leashed and crawling like dogs. One picture showed Sgt. Smith threatening a cowering inmate with his growling, unmuzzled black Belgian shepherd only inches from the prisoner’s face.

The military jurors found him guilty on six of 13 counts, including conspiring with another soldier to use their dogs to make detainees urinate and defecate on themselves. They also found him guilty of ordering his dog to lick peanut butter off a male American soldier’s genitals and the breasts of a female American soldier while another soldier videotaped the scene. He was sentenced to six months in prison, forfeiture of $2,250 in pay, demotion to private and a bad-conduct discharge after he gets out of prison.

Few would disagree that Sgt. Smith deserves punishment. His is the latest of 10 convictions in the Abu Ghraib detainee-torture scandal – all of them low-level soldiers. The consistent refrain from the White House and the Pentagon has been that the abuse has been committed by a few rogue soldiers or rotten applies. The military justice system seems unwilling or unable to follow culpability up the chain of command.

One of the witnesses in the Smith court-martial was the former head of military intelligence at Abu Ghraib, Col. Thomas M. Pappas, who testified under a grant of immunity. The Baltimore Sun quoted Col. Pappas as testifying that he had approved the use of muzzled dogs after a visit by Maj. Gen. Geoffrey Miller, former commander of the U.S. detention center at Guantanamo Bay, Cuba. He quoted Gen. Miller, or someone from Gen. Miller’s team, as saying that dogs were an effective tool in the execution of interrogation because of the “Arab fear of dogs.” Gen. Miller invoked his right to remain silent.

Right there is the beginning of the unexplored trail up the chain of command. Senior military officers and Pentagon officials, including Defense Secretary Donald Rumsfeld, certainly were aware of a culture that believes that torture (renamed “aggressive interrogation”) is essential in forcing prisoners to tell what they know about the terrorist conspiracy, even though little of value has come from it.

The Bush administration redefined and legalized torture under memos produced by Attorney General Alberto Gonzales when he was counsel to President George W. Bush. Ultimate responsibility rests with the president, who consistently denies that the United States does not torture and insists that abuses are rare aberrations and that they are being adequately investigated and prosecuted.

The Pentagon and the White House can hardly be expected to investigate their own operations. Only full inquiry by Congress or an independent commission can bring an end to a scandal that has shamed Americans and blackened the country’s reputation throughout the world.