Former CIA chief of the Counterintelligence Center Gus Hathaway remembered the morning he saw barbed-wire along the boundary line of East and West Germany. The night before, on Aug. 12, 1961, thousands of Soviet guards began to seal the border, unbeknownst to the CIA’s Berlin Operations Base on the other side. Panicked East Berliners sprinted through openings or tried to climb barriers that morning, but by midday, it was impossible to get past security troops. Any window of opportunity, whether for escape or negotiating, was closed.

“We had one 180 officers in Berlin,” Hathaway told me, “and we didn’t predict a wall was going up. We all thought we would be fired because 180 guys didn’t know about the wall.” While the CIA came to terms with the loss of sources and agents in a barricaded Berlin, West Berliners were caught between despair over being cut off from loved ones in the East and fear that all-out war was imminent.

Similar fears are once again creeping into the American psyche as tensions escalate with Russia and North Korea. The Russian Federation’s possible interference in our elections and lingering influence in foreign policy has ushered in a new paradigm in the U.S-Russia relationship. Just as quickly as the country pivoted from ally to adversary in the years after World War II, we seem to be rushing toward a new chapter that is already steeped in speculation, fueled by parallels between the Cold War and today’s murky conflicts: Russia’s incursions into Crimea and Ukraine, the subsequent buildup of NATO forces in the Baltic states, and the increased threat of nuclear weapons all seem to characterize our dealings with Russia and other threatening states.

But there is another dimension of the Cold War era that we should be reminded of, one that has mostly gone ignored by pundits but must be acknowledged as we embark on another era of simmering mistrust: the human cost.

I was 17 and living in New Delhi when it was leaked to the public that my father, Paul Dillon, was a CIA officer. Up until that summer in 1975, my six siblings and I had always been told he worked for the State Department. An article in the Times of India reported on the tell-all book Inside the Company: CIA Diary by a former CIA officer, Philip Agee. The book revealed CIA operations around the world and the identities of 250 covert officers, including my father, for whom Agee had worked in Mexico City seven years earlier. The book was, of sorts, the CIA’s WikiLeaks scandal of the 1970s.

My father was also with Gus Hathaway the day the Soviets in East Germany initiated the wall. As part of Operation REDSOX, he had been training Soviet refugees to send back to the bloc as undercover agents. For months, he gained their trust and worked alongside them, but after the recruits were parachuted into Soviet territory, they disappeared. My father, in a CIA report obtained via a FOIA request in which he stated his “mental demands” during this period were “considerable,” later learned that his trainees were victims of the infamous British spymaster who’d been working for the Soviets for over 25 years, Kim Philby. “I do not know what happened to the parties concerned,” Philby later wrote in his memoir from the leisure of his retirement in Moscow, “but I can make an informed guess.”

These considerable mental demands affected intelligence officers more frequently than will ever be reported. The CIA and various journalists and historians record the operations that went awry, but the emotional weight is left to the individuals in the field. And often, these individuals, who are carrying out the duties of their countries and shaping the course of diplomacy, are navigating these relationships with varying levels of trauma.

Agents’ mental demands become an unseen player in a cold war, infecting interpersonal relationships and professional abilities. During my father’s tenure, James Jesus Angleton was the CIA’s chief of counterintelligence from 1954 to 1975 and led an obsessive mole hunt that would ultimately debilitate American intelligence from within. Angleton’s descent into paranoia created an environment of suspicion within the agency, one that cost several careers.

It’s not difficult to look at Angleton’s witch hunt and be eerily reminded of today’s atmosphere of suspicion, leaks, and betrayals, not least of the congressional and intelligence investigations into whether Russia colluded with the Trump administration, compounded recently by questions into whether Trump passed classified information to the Russians from an ally in the Mideast. These joint investigations are not unlike the turf wars between the CIA and FBI during the Cold War, letting internal mistrust shape the outcomes. Some of those turf wars centered around assets working in the United States on behalf of our government, made all the more intense and confusing by Angleton’s belief that virtually all Soviet assets, whether recruited or volunteers, were provocations, sent to America to perplex and destabilized U.S. intelligence.

One of Angleton’s most pointed targets of suspicion was a GRU officer working for the U.S. who had, to many high-ranking officers within the division at the time, proven his bona fides with years of reliable and valuable reporting from within the vault of Soviet intelligence, Russian Maj. General Dmitri Polyakov. The highest-ranking, longest-serving asset to serve the U.S. during the Cold War, my father became his handler in New Delhi in 1973, and developed a genuine and personal relationship that resulted not only in some of the most valued information the CIA received during the Cold War, but a close friendship. James Woolsey, Director of CIA under President Clinton, called Polyakov the “jewel in the crown” among American assets, who “kept the Cold War from becoming hot.”

Polyakov worked for the United States for 18 years, until he was betrayed by another infamous insider, CIA mole Aldrich Ames. Most readers can guess what Polyakov’s fate was, and it was made poignantly personal to me when I met his son 24 years later, after learning he’d immigrated to the United States with the help of the U.S. government. His account of his family’s profound, intimate and heartbreaking experience after their father’s arrest and execution is another example, among many, of the real cost of a cold war that is defined as one without open warfare, but clearly not of human cost and suffering.

As the daughter of an officer once on the front lines of espionage working with some of the CIA’s most important assets, it is disheartening to think that history could be repeated for agents and their families, who might face unspeakable loss in the quiet fight to prevent full-on wars. It is for this reason that we must continue to insist on open, diplomatic dialogue before any other walls appear overnight.

Eva Dillon is the author of Spies in the Family: An American Spymaster, His Russian Crown Jewel, And the Friendship That Helped End the Cold War (Harper).