What is less familiar is that, even as American policies evolved in other parts of the world, especially after the failures in Vietnam, the policies in Guatemala did not. Washington's counterinsurgency arsenal melded with the traditional brutality and racism of the Guatemalan army to make a horrifying brew, and the effects outlasted the global threat of Communism itself.

The story starts in 1954, when Gen. James Doolittle wrote a report for a fellow World War II hero, President Dwight D. Eisenhower, on how to use the C.I.A. in the cold war: ''There are no rules in such a game. Hitherto acceptable norms of human conduct do not apply.'' At the time, officers of the C.I.A. were sifting through the documents of an elected leftist Government it had just overthrown in Guatemala, assembling a list of suspected Communists. The new rightist regime, handpicked by the agency, used the list to eliminate by death any potential opposition. That kind of coordination went on for decades.

Newly declassified American documents, for example, place a C.I.A. officer in the room where Guatemalan intelligence officers -- men responsible for death squad killings -- planned their covert operations in 1965. They show that C.I.A. and other American officials played a key role in the latter 1960's in centralizing command structures and communications of agencies that would be involved in death squad killings for years. They contain C.I.A. reports of secret executions of Communist Party leaders by Guatemalan Government agencies in 1966 that Guatemalan officials publicly denied.

They also show that the C.I.A. station in Guatemala City knew that the Guatemalan army was massacring entire Mayan villages while Reagan Administration officials publicly supported the military regime's human rights record. Even after the war was won, the documents reveal, Defense Intelligence Agency officials knew that the Guatemalan military was destroying evidence of torture centers and clandestine graveyards in 1994. Not a word was uttered publicly by the Clinton Administration.

Through the decades, a lone voice of warning belonged to Viron Vaky, a State Department official who had been the Number 2 official in the Embassy in Guatemala. In a long memo of dissent in March 1968, he wrote that the ''indiscriminate'' violence of the counterinsurgency tactics ''present a serious problem for the U.S. in terms of our image in Latin America and the credibility of what we say we stand for.'' Not shirking his own responsibility, he added, ''I feel somewhat like Fulbright says he felt about the Tonkin Gulf resolution -- my deepest regret is that I did not fight harder within the Embassy councils when I was there to press my views.''