One of the most important US intelligence operations in modern history was right in the heart of Moscow, during one of the most dangerous periods of the Cold War.

The years 1979-1985 were a time of many events, such as President Ronald Reagan's "evil empire" speech, the fear of the 1983 US-Soviet war, the death of three Soviet General Secretaries, the shooting down of KAL 007...

During that period, the US Central Intelligence Agency (CIA) received extremely valuable intelligence from a source hidden in a very important Soviet military laboratory.

According to Business Insider, over several years and 21 meetings with CIA officers in Moscow, Adolf Tolkachev, an engineer responsible for supervising the radar development laboratory at a Soviet defense institute, passed information and diagrams of the Soviet Union's new radar system to the US.

Tolkachev tried to convince the CIA that he was trustworthy. Tolkachev spent two years convincing American intelligence officers and diplomats.

And when the CIA decided to trust him, he passed on to the US information about Soviet radar capabilities, which were mentioned in documents on US military and development strategy for the following decade.

Before Tolkachev cooperated with the CIA, US intelligence had no idea that Soviet fighters had "knocked out" radars that could detect targets flying below the plane.

Thanks to Tolkachev, the United States was able to design fighter aircraft capable of carrying nuclear-tipped cruise missiles, taking advantage of the latest Soviet innovations in detecting and exploiting vulnerabilities in enemy radar systems.

The Soviets were unaware that the United States had captured their technological situation. Tolkachev created a military balance between the United States and the Soviet Union, but in Washington's favor.

Tolkachev is also part of the reason why, since the end of the Cold War, Soviet-built aircraft have never shot down a single American fighter.

According to VNN