The Pentagon will take whatever steps necessary to bring those responsible for abusing Iraqi prisoners to justice, Defense Secretary Donald Rumsfeld said Tuesday.

"We're taking and will continue to take whatever steps are necessary to hold accountable those that may have violated the code of military conduct and betrayed the trust placed in them by the American people," Rumsfeld told a Pentagon news conference.

Rumsfeld called the allegations "deeply disturbing," saying the reports of the abuse at Abu Ghraib (search), Baghdad's main prison where stories of Saddam Hussein's torture abound, are "totally unacceptable and un-American."

"I have no doubt that we will take these charges and allegations most seriously," he continued.

But Rumsfeld disputed critics in Congress who have said the Pentagon moved too slowly and asserted that correct military procedures were followed.

"These things are complicated, they take some time," he said of the investigations. "The system works. The system works."

And, lawmakers emerged from a closed-door briefing with Pentagon officials and said similar abuses — though "small in number" — may also have occurred at other Iraqi facilities and in Afghanistan.

"We did not get the full details but were left with the impression that they were relatively isolated and certainly small in number," said Sen. John Warner, chairman of the Senate Armed Services Committee, adding that lawmakers "received assurances this morning that this incident really stands, in terms of the number of allegations, without parallel."

Sen. Carl Levin of Michigan, the top Democrat on the panel, said: "We hope it's a few" individuals. "We don't know how systemic it is."

Secretary of State Colin Powell said the photos "shocked every American" and were "illegal against all standards."

"We'll get to the bottom of this," Powell continued. "But I want to remind the world it was a small number of troops … compared to the hundreds of thousands who have served around the world who have come to build hospitals and schools and restore civil society.

"These wonderful young men and women are distressed some of their fellow soldiers acted in this manner," he said.

The episode is to the U.S. mission in Iraq "in a fundamental way, it's harmful," Rumsfeld said. "It is, we hope, an isolated case."

Soldiers Were 'Following Orders'

Meanwhile, an attorney for a military police officer being investigated in the probe, said in a television interview that the photographs "were obviously staged" in order to manipulate the prisoners into cooperating with intelligence officials.

"They were part of the psychological manipulation of the prisoners being interrogated," said Guy Womack.

"It was being controlled and devised by the military intelligence community and other governmental agencies, including the CIA," Womack said. The soldiers, he said, were simply "following orders."

U.S. Army Brig. Gen. Janis Karpinski, who oversaw the prison at the time, said she was unaware of the activity but that when it occurred, the military intelligence command was in charge of interrogating prisoners. She said the U.S. servicemen and women shown in the pictures would not have been acting like that on their own.

"I think they were being instructed to do some of those things ... they were given instruction initially … for interrogations to effectively take place," Karpinski told Fox News' The O'Reilly Factor.

"I can also say with great confidence that those MPs [military police officers] did not wake up one morning and decide to do those things. It wouldn't occur that way," she continued.

"I'm telling you they were under tremendous pressure to get more actionable intelligence from the detainees."

'No Justification' for Treatment, Says McCain

Senate Minority Leader Tom Daschle of South Dakota, demanded to know why President Bush was not earlier informed of the report and why Rumsfeld and Joint Chiefs of Staff Chairman Gen. Richard Myers have not yet read a two-month old report Pentagon report that contained some of the allegations.

Daschle asked "why, in other words, has there been this extraordinary disconnect, this unbelievable failure of communication, of oversight?"

White House spokesman Scott McClellan said Tuesday that Bush first became aware of the allegations of abuse some time after the Pentagon began looking into it but did not see the pictures until they were made public and did not learn of the classified Pentagon report until news organizations reported its existence.

Warner said briefers told the committee that the sexual humiliation photographed in Abu Ghraib stand out among the other alleged incidents and "very little parallels this elsewhere." And he added, "This is as serious a problem of breakdown in discipline as I've ever observed."

Sen. Edward Kennedy, D-Mass., said he feared allegations made public so far are "the beginning rather than the end."

But Sen. John McCain, R-Ariz., told reporters he was "extremely hopeful that ... this was not a widespread pattern of abuse and that the conduct of the overwhelming majority of Americans is honorable and decent."

McCain, who spent 5 1/2 years as a prisoner of war in Vietnam, said such abuses would not be tolerated or excused.

"The rules for the treatment of prisoners of war are very clear," McCain said. "There is no justification for this kind of treatment."

Rumsfeld said it was "premature" to know if the abuse had existed in other prisons run by the U.S. military, including those in Afghanistan and Guantanamo Bay, Cuba.

Rumsfeld: 'I was Stunned by All of It'

Rumsfeld said he hoped that any damage to the image of the U.S. military in world opinion would improve over time. "I was stunned by all of it," he said. But "the world has seen problems of this type before ... People do things that they ought not to do and that are harmful and that are disappointing and in many instances are disgraceful."

He said he didn't know whether the abuse that had been documented amounted to torture.

Gen. Peter Pace, vice chairman of the Joints Chiefs of Staff, denied any foot dragging.

"There has been no attempt to hide this," Pace said, saying the February report was moving up the chain of command.

Pace said Pentagon officials agreed with the internal Army report's findings that the prisons in Iraq were understaffed for the number of prisoners and that the prison guards were inadequately trained.

On March 20, criminal charges were filed against six military police officers. As many as three of the six cases have been referred to military trial, and others are in various stages of preliminary hearings.

In addition to the criminal cases, seven others — all military police — have been given noncriminal punishment — six got letters of reprimand. Some of the seven are members of the Army Reserve.

Later the Army disclosed that there have been 35 U.S. military criminal investigations into allegations of prisoner abuse and deaths in Iraq and Afghanistan since December 2002. Of those, 10 investigations into deaths and 10 assault inquiries are under way, Maj. Gen. Donald Ryder, the Army's Provost Marshal, told reporters. He visited the Iraqi prison system last fall.

Ryder said that in addition to the pending cases, one homicide case has been completed. Another official said the U.S. soldier who was found guilty in that case was discharged from the service, but the official did not say whether that was in Iraq or Afghanistan. Another official said the soldier killed the prisoner with a rock. Another homicide case that is not yet complete involves a CIA contractor.

Ryder also said 12 other deaths at U.S.-run prisons in Iraq and Afghanistan were found to be of undetermined cause or of natural causes. Another death was ruled a justifiable homicide.

In other developments, the top U.N. human rights agency has opened an investigation into civil rights in Iraq. And, U.S. officials in Baghdad ordered a halt to using hoods to blindfold Iraqi prisoners, a military spokesman said.

Fox News' Teri Schultz and The Associated Press contributed to this report.