The revelation that the CIA secretly co-owned the world’s leading manufacturer of encryption machines, and rigged those devices to conduct espionage on more than 100 nations that purchased them for more than half a century, has generated a number of historical and ethical questions: What did U.S. officials know, and when did they know it, about key episodes in recent world history? How did U.S. policymakers act on the intelligence that was gathered? Did U.S. officials have an obligation, as The Washington Post’s Greg Miller put it, to “expose or stop human rights violations unfolding in their view”? Should the United States have been spying on friends and foes alike?

But the most immediate question has yet to be answered: What should the United States do with the massive trove of intercepted communications it obtained and decrypted, along with the thousands of secret intelligence reports those intercepts generated? Those files are gathering dust in the SCIFs — the sensitive compartmented information facilities — of the CIA and the National Security Agency. Hidden away, the documents represent a history held hostage; they have the potential to significantly advance the historical record, not only on U.S. foreign policy but on key world crises and events (wars, coups, terrorist attacks, peace accords) over more than five decades.

But their value to history, and the lessons they hold, will become apparent only if and when the documents are declassified and made accessible to the public.

‘We can neither confirm nor deny that such documents exist.” That is a standard, official response by the CIA and the NSA to Freedom of Information Act requests seeking the release of classified documentation on past covert operations and espionage programs, especially those that involve signals intelligence. “SIGINT,” in the parlance of the intelligence community, is gleaned from phone transmissions, telexes, emails, satellites and other forms of electronic communication. Perhaps the most sacrosanct secret kept by spy agencies is how they obtain such information.

The exposés in February by Miller and Peter Mueller of the German public broadcaster ZDF, however, confirm the existence of a 50-year-long paper trail of extraordinary SIGINT documentation. Through a leak, those reporters gained access to a 96-page CIA history, along with an oral history compiled by officers of the German intelligence agency, showing how those governments controlled the Swiss company, Crypto AG, that made the encryption machines. The name for this operation was “Rubicon,” and the secret CIA history about it is titled “Minerva,” the code name assigned to company.

The secret history describes how a “handshake deal” between Boris Hagelin, the founder and owner of Crypto AG, and William Friedman, the founding father of American cryptology, set up a system in the early 1950s that allowed the NSA to dictate where the company sold “breakable” communications devices and where it sold unbreakable machines. After the U.S. and German governments bought the company for $5.75 million in 1970, Washington “controlled nearly every aspect of Crypto’s operations,” among them “hiring decisions, designing its technology, sabotaging its algorithms and directing its sales targets,” according to The Post’s report. It monitored Egypt’s negotiating strategies during the 1978 peace talks with Israel led by President Jimmy Carter at Camp David; Iranian mullahs amid the 1979 embassy hostage crisis in Tehran; and more than 19,000 encrypted messages during the Iran-Iraq War. The United States sent intercepted Argentine messages to its ally Britain during the 1982 Falklands War.

In Latin America, a major market for the Crypto machines, the Minerva program let the CIA listen in as generals plotted coups in Chile, Argentina, Uruguay, Brazil, Paraguay and Bolivia, and then waged the “dirty wars” of repression that followed. The rigged machines also enabled the CIA to surveil the sinister consortium of those nations’ secret police services, known as Operation Condor, which orchestrated covert, cross-border rendition and assassination missions against opponents in Latin America, Europe and even the United States.

The intelligence gathered on Operation Condor carries a humanitarian value that goes beyond its historical importance. These records have the potential to shed light on the fate of Condor’s victims, many of whom remain desaparecidos — disappeared. The documents are also likely to contain evidence that could help hold the perpetrators of those and other human rights crimes legally and historically accountable as trials continue in countries like Argentina and Chile. Perhaps most significantly for U.S. security interests, the Condor papers may reveal how and why U.S. intelligence officials failed to deter an act of international terrorism on the streets of Washington: the Sept. 21, 1976, car-bombing that killed former Chilean ambassador Orlando Letelier and his 25-year-old colleague, Ronni Karpen Moffitt.

These are secrets the government has kept hidden for decades. The NSA, for instance, resisted FBI and Justice Department requests for assistance in the investigation of the Letelier-Moffitt assassination. “It would be very unfortunate if one agency of our Government possessed information which may be relevant to this murder and would not disclose it to us,” the Justice Department prosecutor, Eugene Propper, complained in a classified memo (later declassified) more than a year after the terrorist attack.

The NSA also moved to sequester and classify papers donated to the Virginia Military Institute by Friedman, Hagelin’s NSA handler, when it discovered their existence.

More recently, the keepers of the secrets have demonstrated that documents related to Crypto AG and signals intelligence can be declassified — albeit with extensive redactions — without damaging U.S. security interests. The NSA has declassified older examples of its daily signals-intelligence summary that probably contain information from the Minerva project. As part of President Barack Obama’s Open Government Initiative, in 2015 the NSA posted some 7,600 documents relating to Friedman’s career, including censored versions of his communications with Hagelin in the 1950s. The NSA “periodically conducts ‘Special Topical Reviews’ of categories of records, such as the Gulf of Tonkin, USS Liberty, UKUSA, and posts those records,” according to a statement on its website. “In accordance with the federal Open Government initiative, we will identify subjects and records for which there is a general public interest.”

There is certainly a “general public interest,” as well as a global public interest, in the Minerva papers. With the history of one of their most successful espionage operations now in the spotlight, the NSA and the CIA could undertake a “special topical review” of those documents that proceeds along these lines:

First, the CIA could quickly review and declassify the 96-page Minerva history. Now that it has leaked, these operations are no longer a secret. This would allow the U.S. government to take credit not only for the intelligence achievements of Minerva but also for making the history available for public scrutiny.

Second, the NSA and the CIA could centralize the files that served as the basis for the Minerva history and review those records for declassification over the next two years.

Finally, the agencies could divide the papers into several special topical reviews: a Condor collection, an Iran hostage crisis collection, an Iran-Iraq War collection and so on. Each grouping would combine the raw decrypted communications on those topics with the finished intelligence reports that drew on those intercepts. A series of releases, similar to ones the NSA and the CIA have done in the past, could be scheduled over the next decade. In particular, documentation related to human rights cases in Latin America and elsewhere could be given special priority and made accessible to legal authorities who are prosecuting crimes against humanity.

Clearly, officials at the CIA and the NSA understand the value of history and the ongoing relevance of these documents. That is why they spent considerable time, effort and taxpayer resources to compile the Minerva history — to help the next generation of intelligence officials understand the lessons of the past and their implications for the future. Presumably, this internal history would be shared on a “need to know” basis.

But the public at large also has a need to know — and an even greater right to know. The Minerva intelligence operations were carried out to advance our national security. Now, the records they generated can be used to secure our history.

Twitter: @peterkornbluh