In 1958, General Drozdov posed as a Silesian in Leipzig, then in Communist-controlled East Germany, and was concerned that he might slip up.

“I spent hours going around West Berlin, listening to the speech of Germans, taking in its emotional color, and tried to take on their manner of behavior,” he wrote. He attended lectures at a theater school and read everything he could find — even a brochure about the behavior of male visitors to the public toilet, to get a grasp of local vulgar humor.

In 1962, he played a key role in a famous exchange of captive spies between the Soviet Union and the United States.

The captured American was the military pilot Francis Gary Powers, who had been held for 21 months after his U-2 reconnaissance plane, operated by the Central Intelligence Agency, was shot down by the Soviets in 1960. In the United States, Vilyam Fisher, who went by the alias Rudolf Abel, had been seized by the F.B.I. and convicted of espionage in 1957.

General Drozdov, inspired by a nameplate saying “Doctor Drews J.” that he happened to see, took on the persona of Jurgen Drews, Abel’s purported German cousin. His interaction with Abel’s lawyer, James B. Donovan, led to the exchange of Abel and Powers on the Glienicke Bridge, between West Berlin and Potsdam in East Germany. (The episode was dramatized in the 2015 Hollywood movie “Bridge of Spies.”)

General Drozdov later served in China during the Cultural Revolution, and amid Sino-Soviet tensions. In 1975 he was sent to New York, where he worked undercover as the Soviet Union’s deputy representative to the United Nations.

He did not take kindly to betrayal. He described Arkady Shevchenko, the Soviet diplomat at the United Nations who defected to the United States in 1978, as “a Judas.”