The United States believed that the Colombian military was behind a wave of assassinations of leftist activists and yet spent the next two decades deepening its relationship with the Colombian armed forces, newly released documents show.
The Central Intelligence Agency had evidence that the Colombian military had provided a target list to paramilitaries who killed 20 banana plantation workers in a high-profile massacre, the documents show, but went on to send billions of dollars in aid to the Colombian government.
On Tuesday, a truth commission in Colombia will release a long-awaited report that attempts to build an extensive history of the nation’s decades-long internal conflict, in which at least 260,000 people died.
The report, written as a result of the country’s 2016 peace deal with its largest insurgent group, the Revolutionary Armed Forces of Colombia, is meant to be used by Colombia’s next government to create policies that move the country toward a lasting peace. It could help shape Colombia’s future relationship with the United States.
Among the themes explored in the report is the role of the U.S. government, which spent decades funding and training the Colombian military in its fight against the FARC and the drug economy that financed their insurgency.
And among pieces of evidence used to write Tuesday’s report are thousands of declassified U.S. documents gathered and organized by the National Security Archive, a Washington-based nongovernmental organization that specializes in supporting post-conflict truth commissions.
A digital library of the documents will be published in August. But the National Security Archive provided The New York Times with some documents ahead of time. They reveal that the United States had decades of knowledge of alleged crimes committed by the Colombian military — “and yet the relationship continued to grow,” said Michael Evans, director of the Archive’s Colombia project.
Particularly demonstrative, he said, are a series of C.I.A. operational reports not normally available to the public, even after a record request.
One report, written in 1988 during a period in which leftist activists were being killed on a regular basis, found that a wave of assassinations carried out against “suspected leftists and communists” was the result of “a joint effort” between the intelligence chief of the Colombian Army Fourth Brigade and members of the Medellín narcotics trafficking cartel.
Many of those killed were associated with a party called the Patriotic Union. The report said it was “unlikely” that this took place “without the knowledge of the Fourth Brigade commander.”
Later in the document, a C.I.A. officer writes of a 1988 massacre in which 20 farmworkers, many of them union members, were killed. The C.I.A. officer indicates that the U.S. government believed the assassins “obtained the names of their intended targets” from the Colombia Army’s 10th Brigade intelligence unit.
Other documents show that the United States knew oil companies were paying paramilitaries for protection, and that at least one company gathered intelligence for the Colombian military.
One company was “actively providing intelligence on guerrilla activities directly to the Army,” according to the C.I.A., “using an airborne surveillance system along the pipeline to expose guerrilla encampments and intercept guerrilla communications.”
The Colombian Army “successfully exploited this information and inflicted an estimated 100 casualties during an operation against the guerrillas” in 1997, according to the report.
Another document, written in 2003, hints at one of the grimmest chapters of the war, called the false positives scandal. In that case, the Colombian military is accused of killing thousands of civilians during the presidency of Álvaro Uribe and trying to pass them off as combat deaths, in an effort to show it was winning the war.
In recent court testimony in Colombia, former soldiers have said they felt pressured to kill fellow Colombians by higher-ups.
A July 2003 memo to Donald Rumsfeld, then the secretary of defense, from the top Pentagon deputy for special operations celebrates a significant rise in combat kills since Mr. Uribe took office took — 543 in just six months, compared with 780 during the last two years of the previous government.
The document is titled “recent successes against the Colombian FARC.”