Fifty years on, the US role in overthrowing the socialist government of Salvador Allende is not a secret. But as documents that surfaced over the past couple months should remind us, there’s still a whole lot that’s being kept from us about this shocking crime.

This past August saw several documents released that shed added light on the Richard Nixon administration’s involvement in the coup’s plotting, obtained through a Freedom of Information Act (FOIA) request by National Security Archive analyst Peter Kornbluh. While we’ve long known that Nixon and his secretary of state Henry Kissinger worked aggressively to overturn Chile’s election in 1970, these releases give us a fuller picture of how exactly that was carried out.

One set of documents, for example, details previously unknown meetings shortly after the election between US officials, including Nixon, and Agustín Edwards, a right-wing Chilean media tycoon. Kornbluh points out that, according to a declassified memo handwritten by then CIA director Richard Helms, it was only six hours after this meeting that Nixon brought Kissinger, Helms, and Attorney General John Mitchell into the Oval Office and ordered them to come up with a “game plan” within forty-eight hours to stop Allende from being inaugurated. We’d previously known that Edwards and Helms had taken part in a meeting days after the election, when the conservative magnate had discussed how a coup might be carried out.

According to a 1975 Church Committee report on CIA involvement in Chile, its funding for Edwards’s right-wing newspaper El Mercurio, to the tune of roughly $2 million after Allende’s victory alone, was “by far the largest — and probably the most significant — instance of support for a media organization” in the country by the CIA. A postmortem by the CIA, the report explained, “concluded that El Mercurio and other media outlets supported by the Agency had played an important role in setting the stage” for the successful 1973 coup through their unrelenting propaganda campaign against Allende. It was all just one part of what the report described as the “continuous and massive” US covert action in the country between 1963 and 1973.

Another document contains a detailed outline of a CIA debriefing with Edwards about coup plans, including logistics and which Chilean military officials would be needed and could be counted on to carry out the plot. The CIA was told that the coup leaders would need “several clear and specific guarantees” from Washington to act, like “immediate and possibly massive economic support” and logistical support in the form of weapons, transport, and equipment. They were also told that the national police, which had “been under intense pressure from extreme leftists” and were the country’s “largest and probably the best trained and best armed uniformed force,” would likely join in the coup.

While Augusto Pinochet, the former military general who ultimately became Chile’s dictator after Allende was toppled, apparently wasn’t in the lineup of military men discussed, General Carlos Prats was. The memo notes that Edwards singled out Prats — then the second-highest ranking military official, soon to ascend to the highest post and hold a variety of other positions under Allende, including vice president — “as the most important figure in any military action which might be taken.”

“He is well-regarded by nearly all army officers and possesses the qualities which other officers lack to become a rallying point for action,” the memo states, while noting that there was “no clear idea of this general’s political attitudes.” The memo also notes “the longstanding enmity” between Prats and General Roberto Viaux, who would end up being one of the principal coup leaders, as a potential obstacle.

Sure enough, Prats was an opponent and fierce critic of the eventual coup, and was considered a viable challenger to Pinochet’s rule after it. He was, in the end, assassinated while in exile in Argentina as part of Operation Condor, an international campaign of repression by South America’s dictatorships against their political enemies.

Also mentioned was General René Schneider, then Chile’s highest-ranked military official and another coup opponent, and whose “removal,” as the CIA put it that October, became central to the 1970 coup attempt. Edwards “did not believe Schneider would take any part in possible action against Allende’s assumption of the presidency and that if he were named Minister of Defense, as has been rumored, it would be a ‘real mess,’” the September memo states.

Schneider ended up being inadvertently murdered in the process of being kidnapped by the coup-plotters the following month, shocking the country and rallying the military and political elite behind the constitutional transfer of power, turning the 1970 coup attempt into a failure. In a transcript of a phone conversation between Nixon and Kissinger after the killing, another of the documents released in August, the two characteristically absolve themselves for their own failure and blame the Chileans.

“The next move should have been a government takeover, but that hasn’t happened,” Kissinger complains. Asked by Nixon if he meant that the murder should have meant that “people would get so disturbed that they would take over the government,” Kissinger replies, “That was the theory but they’re a pretty incompetent bunch.”

“They’re out of practice,” says Nixon.

A handful of other documents to do with the Chilean coup were more recently declassified by the White House at the end of August, thanks to lobbying from left-wing Chilean president Gabriel Boric and progressive members of the US Congress, this time dealing with the successful 1973 effort to depose Allende. Partly, these declassified pages from the president’s daily brief — US intelligence’s daily summary on the most pressing national security information for the president — give some insight into the pressure and peril facing Allende days before his death and how he hoped to navigate it.

According to a September 8 brief, Allende believed the military would ask for his resignation “if he does not change his economic and political policies,” and didn’t think his supporters would be able to win or even mount an armed resistance, concluding that only a political solution could resolve things.

“Allende seemed to be trying to convince [redacted] that the situation is serious and requires cautious handling, and that some tactical political retreats may be in order,” reads the memo.

While less sensational than the earlier August release, the documents also show that Nixon was well aware of “the possibility of an early military coup attempt” as early as three days before it took place. The silence from Washington that followed was likely and understandably viewed as a green light by the coup plotters, given the administration’s ardent involvement in the coup attempt three years earlier.

These are not necessarily the most groundbreaking revelations, since it’s long established that both Nixon and the CIA at least had foreknowledge of the 1973 coup, and probably much more extensive involvement. But that begs the question of why these documents have remained classified for so long, especially given, as Kornbluh put it, that the documents “contain not a single sentence that could compromise US national security.”

It also begs another question: What else is being kept from us about this event?