The Obama administration on Monday released more than 1,000 pages of newly declassified documents relating to U.S. policy toward Argentina’s “dirty war” of the late 1970s and early 1980s.

The documents, most from the administration of President Jimmy Carter, reveal a near-constant internal tension between U.S. eagerness to push human rights as Carter’s signature foreign policy issue, and concerns that cutting off aid and trade with Argentina’s ruling military junta could be counterproductive and might push it toward a closer relationship with the Soviet Union.

“When we take actions toward Argentina, which are interpreted as punitive, we not only enrage the right-wing ideologues, we also arouse the business sector and the media in the U.S.,” Zbigniew Brzezinski, Carter’s national security adviser, wrote in a March 1979 memo to then-Secretary of State Cyrus Vance.

President Obama announced the declassifications in March, on a visit to Argentina that coincided with the 40th anniversary of the coup that brought the junta to power.

“I believe we have a responsibility to confront the past with honesty and transparency,” Obama said at the time. An initial tranche of the documents, the same ones as those now made public, were presented to Argentine President Mauricio Macri by Secretary of State John F. Kerry during a visit to Buenos Aires last week.

The State Department released 4,700 pages of its own documents – most of them official communications from the U.S. Embassy in Buenos Aires – that were declassified in 2002 by the administration of President Clinton. Others have been released since in response to requests from Argentine judges investigating the abuses of the junta years and to Freedom of Information Act requests from U.S. organizations such as the National Security Archive.

Many of the newly released documents relate to White House policy deliberations and come from Carter’s presidential library in Atlanta. Additional declassifications, from the libraries of former presidents Gerald Ford, Ronald Reagan and George H.W. Bush, are to take place over the next year. Overall, the records begin in 1975, the year before Argentine President Isabel Perón was overthrown, and end with the restoration of civilian government at the end of 1983.

The seven-year “dirty war” was marked by the disappearance of tens of thousands of people, most of whom were tortured and killed by the military in the name of counterterrorism. While a violent Marxist movement in Argentina was eradicated, most of those purged during the conflict the military defined as “World War III” included student, union, opposition and human rights leaders.

The Monday release, posted on the website of the Office of the Director of National Intelligence, “marks an important step forward in the quest for truth, justice and historical accountability,” said Carlos Osorio, director of the National Security Archive’s Southern Cone project.

Earlier document declassifications related to Chile, Guatemala and El Salvador have revealed not only information about how those military governments operated but also the extent of U.S. involvement in supporting them.