White House advisers convene secret sessions on the political dangers of revelations that American troops committed atrocities in the war zone, and whether the president can delicately intervene in the investigation. In the face of an increasingly unpopular war, they wonder at the impact on support at home. The best way out of the war, they agree, is propping up a new government that can attract feuding elements across a fractured foreign land.

With an obvious resonance to current events, the National Archives and Records Administration released 50,000 pages of previously classified documents from the Nixon administration today that reveal how all that president's men wrestled with issues that eerily parallel problems facing the Bush administration.

There are many significant differences between the wars in Vietnam and in Iraq - a point that senior Bush administration officials make at any opportunity. But in tone and content, the Nixon-era debate about the impact of that generation's war - and of war crimes trials -- on public support for the military effort and for White House domestic initiatives strikes many familiar chords.

As the Nixon administration was waging a war and trying to impose a peace in South Vietnam, it worried intensively about how the 1968 massacre at My Lai by American troops would hurt the war effort, both at home and in Asia.

My Lai "could prove acutely embarrassing to the United States" and could affect the Paris peace talks, Defense Secretary Melvin R. Laird warned President Richard M. Nixon. "Domestically, it will provide grist for the mills of antiwar activists," Mr. Laird said.

Documents show how the Nixon White House fretted over politics and perception, much as the current Bush White House has during the Iraq war, and that the Nixon administration feared that reports of the mistreatment of civilians could be ruinous to its image.