But the pressure apparently worked. Eventually, the radiation tapered off, and the American embassy returned to work as normal. But the microwave beam never fully disappeared, running through the tail end of the 1980s — meaning that the beam continued, off and on, for almost the entirety of the Cold War, making it arguably the Soviets’ longest-running anti-American program of the entire era.

At the time of Brezhnev’s outburst, the claim that no one had “fallen sick” may have been true. But by the time Schumaker had arrived at the embassy, when staffers had finally been made aware of the microwave beam’s existence, that claim was increasingly faulty. One study discovered that as many as one-third of the embassy’s employees had higher white blood counts than normal, and that “blood counts returned to normal a few weeks after departing Moscow.”

That’s not necessarily confirmation that the Soviets’ microwave radiation caused the elevated blood counts. But at the time, a pair of former American ambassadors stationed in Moscow had recently died from cancer, and another had been diagnosed with a “severe blood disorder.” As the Foreign Service Journal summed up, “To most Moscow staffers, it just seemed like too much of a coincidence.”

Indeed, new findings are now calling into question the studies and claims that officials relied on back then to dismiss health concerns.

To Schumaker, that reality hit home a few years after he returned from Moscow, when a doctor diagnosed him with chronic lymphocytic leukemia — a disease that emerged after he’d arrived in Moscow in “perfect health.”

“I have always considered Moscow microwaves to be a prime suspect,” Schumaker remembered. “[The diagnosis] came as a shock, as I have no family history of leukemia. It is a puzzle to which there is still no answer.”

It’s a puzzle to which diplomats struggling with Havana Syndrome symptoms can relate — and in more ways than just the physical. Much like the Moscow Signal experience, those suffering from Havana Syndrome have continued to be dismissed by many, including by officials in Washington, as cranks or hypochondriacs. And especially after the recent intelligence conclusions, those dismissals will likely continue. “You can say with certainty that the U.S. government’s reaction to reports of the Havana Syndrome was typical — and almost exactly the same as in the case of Moscow Signal,” Schumaker, who survived his leukemia diagnosis, told me. “It was first the bureaucratic impulse to push everything away and say, ‘It’s not happening, it’s not happening — these people are just imagining things, it’s all in their heads.’ And it was the same sort of thing with Havana Syndrome.”

If anything, the Moscow Signal and the Havana Syndrome are something of a mirror image of one another. In the former, we have confirmation that the Soviets spent decades saturating American diplomatic staff in microwave radiation — though the link to subsequent symptoms remains ultimately unclear. In the latter, we have a clear constellation of symptoms (and a far broader range of targets) — but no ultimate, identifiable cause. And after the recent conclusion from the intelligence agencies, any answer appears further away than ever.