The State Department with the CIA last week declassified two 50-year-old documents that had been withheld from public view that shed new light on the military coup in Chile that overthrew the country’s elected president.

One is then-President Nixon’s intelligence briefing notes from the day of the coup, Sept. 11, 1973, marked top secret “For the President Only.” The National Security Archive, a non-governmental research organization, described the papers as some of “the most historically iconic of missing records” on the coup.

“[T]hey contained information that went to President Nixon as a military takeover that he and his top advisor Henry Kissinger had encouraged for three years came to fruition,” the National Security Archive, which studies and stores vast troves of formerly secret official documents, said in a statement.

The coup led to the death of the Chilean president, leftist leader Salvador Allende, and installed years of brutal right-wing military rule headed by Gen. Augusto Pinochet in what had been until then a promising young democracy.

While the newly declassified documents don’t substantially change the story, they reveal the considerable amount of detail that Nixon knew about the steps leading to the coup. In addition to the briefing papers from the day of the coup, a second document recounts Nixon’s briefing from two days before the military takeover.

Thousands of Chilean civilians were killed, imprisoned or tortured, with some rounded up by the army and held in a stadium where they met their death.

Within a few years, neighboring Argentina also fell to a brutal military dictatorship, while other countries including Bolivia and Paraguay followed suit. It was a difficult and torturous era in Latin America that slowly shifted to more progressive democracies, although the political dynamics have continued to change, with the return of the right and authoritarians in some countries.

The full extent of the role of the CIA and other U.S. players in the Chile coup has long been debated. While the Nixon administration was not thought to have had a direct hand in executing the coup, it appeared to fit the pattern of numerous so-called regime changes the U.S. clandestinely engineered over the decades in Latin America, Iran and beyond.

As Chile prepares to mark the 50th ^{anniversary of the coup that forever changed its course — and that still stands as one of the seminal events in the continent’s history — officials there are eager to learn as much as possible about the back story of those events.}

Thousands of documents related to the Chile coup have been declassified over the years. The State Department said Friday it was releasing the new batch now “to allow for a deeper understanding of our shared history” and in the spirit of cementing good relations between Washington and Santiago, where a moderate leftist president took office last year. The Biden administration has sought to nurture friendly relationships with moderate leftists in Latin America as a counterbalance to more radical leaders in the region.

Chilean officials said the release of the documents came in response to their petition ahead of the ^{50th anniversary.}

Declassification of the files “promotes the search for truth and reinforces our nations’ commitment to democratic values,” Chilean Foreign Minister Gloria de la Fuente said in thanking the Biden administration.

“Democracy is memory and also future,” she said.

The coup in Chile saw smoke rise from the besieged presidential palace, La Moneda, as military aircraft bombarded it, an indelible image for many in Latin America.

Nixon and Kissinger, secretary of State during Nixon’s final year in office, were no fans of the Allende government and its leftist leanings, and had sought to block it from assuming office in the first place. The U.S. government of that era favored Pinochet, who for most of his 17 years of rule had good economic and military ties with Washington as he repressed many of his own people, but also built up the Chilean economy.

In Pinochet’s later years, several countries attempted to prosecute him for crimes against humanity, but he died in 2006 before those efforts progressed.

Peter Kornbluh, a researcher for the National Security Archive who has specialized in Chile for years, welcomed the new declassification but questioned why it had taken so long since the information posed no threat to national security. Keeping the documents secret all this time was a “travesty,” he said.

“Key collections of U.S. records that remain secret would be invaluable to an informed debate over the coup and CIA ties to the Chilean secret police,” Kornbluh said, also noting the need to learn more about Pinochet’s role in ordering the 1976 assassination of an Allende-era diplomat, Orlando Letelier, in Washington.

Letelier, a vocal critic of Pinochet, was killed in a car bombing that the U.S. intelligence community said was ordered by Pinochet.

In the newly declassified documents, Nixon is told in an intelligence briefing three days before the coup that it is brewing.

“Navy men plotting to overthrow the government now claim army and air force support,” Nixon was told, according to the declassified briefing document.

Nixon was then erroneously told that the coup does not have broad military support.

“Should hotheads in the navy act in the belief they will automatically receive support from the other services, they could find themselves isolated,” the CIA briefer told Nixon.

Then, on the day of the coup, the CIA told Nixon that Chilean military officers were “determined to restore political and economic order” in the country, an appealing patina placed on the revolt.

Chile’s ambassador to the United States, Juan Gabriel Valdés, said the newly declassified documents further demonstrate U.S. meddling in Chile’s domestic affairs for years.

The documents “show a very painful history for both our countries,” Valdés said in a telephone interview from the Chilean Embassy in Washington. U.S. efforts to block the left in Chile began in the 1960s and 70s and then took on “global dimensions” under Nixon and Kissinger, he said, “causing a steady weakening of our institutions and democracy.”

Valdés said the positive side was an eventual series of U.S. investigations into excesses by the CIA and other intelligence organizations, and the emergence of human rights activism that pushed abuses into the spotlight and to the center of some U.S. policies.

“That transformed the Chile cause,” he said.