Many Americans regard President Donald Trump’s relationship with the Kremlin as uncomfortably cozy. Some, top intelligence officials among them, believe our president has a concealed relationship with Russia, and that it’s nothing new.

To anyone versed in counterintelligence, Trump’s summer 1987 inaugural visit to the Soviet Union, ostensibly to develop Moscow’s never-developed Trump Tower, looks like Ground Zero. The KGB habitually monitored visits by Western VIPs, and since Trump’s junket came by invitation of the Soviet foreign ministry, it’s certain that his trip did not escape the KGB’s attention.

KGB veterans have said as much. Oleg Kalugin, once the youngest general in the KGB and an expert on counterintelligence, confirmed to author Craig Unger “that Trump had fun with lots of girls during that trip and he was almost certain that the KGB had kompromat [compromising material] on that.” Since Kalugin spent several years in the 1980s as the deputy chief of the KGB’s office in Leningrad—a city visited by Trump in 1987—it’s safe to assume that his comment was not speculative.

Subscribe to Observer’s Politics Newsletter

It’s always seemed suspicious that, a few weeks after returning from the USSR, the notoriously skinflint Trump spent over $94,000 for full-page ads in major newspapers across the country lambasting American alliances around the globe. Urging Washington to ditch freeloading allies—a mantra our president has stuck with to the present day—just happened to mesh nicely with Moscow’s foreign policy goals. Any investigation into President Trump’s possible secret relationship with Russian intelligence should therefore begin in the fateful summer of 1987.

Or should it? There’s new evidence that Moscow’s spies may have gotten close to Donald Trump years earlier, long before he sojourned to the Soviet Union.

In The Guardian today, Luke Harding explains that Czechoslovak intelligence, a junior partner of the KGB, seems to have been rather close to Donald Trump as far back as the late 1970s. During the Cold War, Prague’s State Security or StB cultivated Western rising stars (including current British Labour party leader Jeremy Corbyn) as possible spies. They had high interest in Donald Trump, given his bright future in New York and beyond.

Trump came to the StB’s attention due to his relationship with his first wife Ivana (née Zelníčková), a Czech model he was married to from 1977 to 1992. When Ivana moved to America to live with her new husband, the StB kept tabs on her and her family, as has been known for some time. Her father, Miloš Zelníček, collaborated with the StB, sharing information on his daughter and her new life.

This was normal in the East Bloc during the Cold War, when the Communist state security apparatus had enormous power and citizens with relatives living in the West had little choice but to collaborate if they wished to stay in touch with loved ones abroad. Most of what Zelníček shared with the StB about his daughter and son-in-law appears mundane, of interest only because decades later Trump became the American president.

Harding’s report cites secret StB write-ups of operational contacts between their agents and Donald Trump, including the improbable September 1989 visit to Trump Tower in Manhattan by three officials from Czechoslovakia’s model collective farm. The junket was an StB secret operation, though what intelligence value they gained isn’t obvious.

More interesting is an StB report from November 1979—its source was Ivana’s father—detailing Mrs. Trump’s recent visit to her family in Moravia, accompanied by her then-two-year-old-son, Donald Jr. Its assessment appears anodyne:

The StB discovered that Ivana was no longer a model and was now “helping her husband in his business activities”—designing the interiors of Trump-financed buildings. Donald Jr. had two nannies—one American, one Swiss—and had recently fractured his leg. And: “Her husband is connected to the election campaign of the current US president [Jimmy] Carter”.

Many StB foreign intelligence operations focused on monitoring citizens living abroad like Ivana, keeping tabs while trying to leverage them for espionage purposes. Although existing StB files don’t indicate that Donald Trump himself was ever recruited by the StB, the November 1979 report includes a tantalizing fact, namely that among the StB organizations copied on it for distribution was the service’s 1st Directorate, the foreign intelligence arm. Specifically, its 23rd Department was copied on the report.

The highly secretive 23rd Department was no ordinary StB office, but part of the elite Illegals sub-directorate. Illegals were the StB’s crème de la crème, hand-selected deep-cover spies dispatched to the West, without the benefit of diplomatic protection; if caught, they were on their own. They posed as ordinary people, often immigrants, but they reported to the StB. The 23rd Department had the demanding job of selecting, training, and managing Illegals in the field. There was no more sensitive office in the service.

Why was the super-secret 23rd Department copied on a mundane information report about the Trump family? To those versed in the ways of Soviet bloc espionage, there can only be one answer: Because the StB either had (or was planning to have) an Illegal close to the Trump family. The service’s effort to keep tabs on Ivana Trump and her husband in America, mainly through her father, was not the real secret here.

Who was this mystery spy? It wasn’t Ivana, given how the StB refers to her in its paperwork. We may never know. Although many StB files survive, some were destroyed with Communism’s collapse. We know that Prague had a star Illegal operating in the United States in 1979: Karl Koecher, who emigrated to America in 1965 and worked his way into power circles on the Potomac. Koecher managed to get a job with the CIA, a coup for the StB, who ran Koecher jointly with the KGB (a common arrangement, since the Soviets were the senior spy partner here), although the Soviets had intermittent doubts about Koecher’s loyalties.

Until his arrest by the FBI in 1984, Koecher passed numerous American secrets to Prague and Moscow, and in the late 1970s he was living in New York City, where he moved after leaving the CIA. He taught philosophy while his wife Hana sold diamonds; libertines by night, they were stars in the disco-era swinging scene. Was Karl Koecher in contact with the Trump family in 1979? If not, then who was the StB Illegal in question?

At last report, Karl Koecher is in his mid-80s, living in the Czech Republic, laying low and avoiding the limelight. Jaroslav Jansa, an StB officer who worked the Trump case in the 1980s, recently refused to discuss the matter, telling reporters “You are trying to put me in the tomb.”

It’s worth asking what’s so dangerous about a legacy spy case almost three decades after the Cold War’s end.