The report by Navy Vice Adm. Albert T. Church said the pressure was not excessive. The investigation could find no "single, overarching reason" why prisoners under U.S. control were abused at the Abu Ghraib prison complex in fall 2003 and elsewhere in Iraq and Afghanistan.
"He could find no policy promulgated by the Department of Defense that condoned torture or the abuse of prisoners," said CBS News Military Consultant Jeff McCausland, who spoke to Church Wednesday.
Command pressure for more intelligence was to be expected in a battlefield setting, Church wrote.
"We found no evidence, however, that interrogators in Iraq believed that any pressure for intelligence subverted their obligation to treat detainees humanely," he wrote in a summary of his findings.
Church, a former Navy inspector general and now director of the Navy staff, was presenting his 21-page report to Congress on Thursday.
Church concluded that no civilian or uniformed leaders directed or encouraged abuse, and his report holds Defense Secretary Donald H. Rumsfeld and other top defense leaders largely blameless on the narrow question of pressuring interrogators as well as the larger matter of interrogation policies.
"We found no evidence to support the notion that the office of the secretary of defense (or other military or White House staff) applied explicit pressure for intelligence or gave 'back channel' permission to forces in the field in Iraq or in Afghanistan" to exceed the bounds of authorized interrogation practices, the report said.
"I guess you could say there is no 'smoking gun' that links Secretary Rumsfeld or other senior Department of Defense officials with abuses such as we saw at Abu Ghraib in Iraq," said McCausland, a retired Army colonel who is now a professor of leadership at the U.S. Naval Academy.
Church conducted more than 800 interviews and reviewed the conclusions of several other investigations. His main purpose was to trace the development and implementation of interrogation policies and techniques and to search for connections to the reported abuses.
"We found no link between approved interrogation techniques and detainee abuse," he concluded.
The review did cite, however, a number of "missed opportunities" in the development of interrogation policies.
Among the missed opportunities was a failure to provide commanders in Iraq and Afghanistan with specific and early guidance on interrogation techniques. "We cannot say that there would necessarily have been less detainee abuse had these opportunities been acted upon," Church wrote.
Had that guidance been provided earlier, "interrogation policy could have benefited from additional expertise and oversight," he wrote.
The Church report also disclosed that the top U.S. commander in Iraq, Army Gen. George Casey, who arrived there last summer, approved on Jan. 27 a new, more restrictive interrogation policy for Iraq.
Casey's new policy "provides additional safeguards and prohibitions, rectifies ambiguities" and requires that commanders report to Casey their compliance with the policy, the report said.
The probe also found, in the cases of detainee operations in Iraq and Afghanistan, that the dissemination of approved interrogation policy to commanders in the field was generally poor. And in Iraq in particular it found that compliance with approved policy guidance was generally poor.
By contrast, compliance with the authorized interrogation methods was in nearly all cases exemplary at the U.S. naval facility at Guantanamo Bay, Cuba, where terrorism suspects have been held since January 2002, the report said. It attributed this to strict command oversight and effective leadership, as well as adequate resources.
The review was done last summer. It is among several triggered by disclosures last spring of prisoner abuse at the Abu Ghraib prison complex in Iraq. Church was directed to look at how interrogation policies were developed and implemented from the start of the terror war in fall 2001.
"An early focus of our investigation was to determine whether DOD (Department of Defense) had promulgated interrogation policies or guidance that directed, sanctioned or encouraged the abuse of detainees. We found that this was not the case," the Church probe concluded.
"Even in the absence of a precise definition of 'humane' treatment, it is clear that none of the pictured abuses at Abu Ghraib bear any resemblance to approved policies at any level," it added.
Church did not directly investigate the Abu Ghraib matter or address questions about accountability for senior defense officials involved in interrogation policy. Both of those matters have been investigated by others.
While the problems cited by Church in the dissemination of interrogation policy guidance to commanders in Iraq and Afghanistan were found to be "certainly cause for concern," Church concluded that "they did not lead to the employment of illegal or abusive interrogation techniques."
However, "they also found that lessons learned from other conflicts on the treatment of prisoners really had not been well incorporated, which may have caused some of the problems that we saw, and lastly, that no guidance was provided to Central Command on how to treat prisoners," said McCausland.
Church examined the 187 Pentagon investigations of alleged prisoner abuse that had been completed when he finished his work last September. He counted 70 of those investigations as having substantiated acts of abuse. In six of the 70 cases, the prisoner died. Of the 70, only 20 were related to interrogations; the other 50 were not associated in any way with questioning, he said.