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. Last Updated: 07/27/2016

Legendary Soviet Spy Feklisov is Dead at 93
A KGB master agent who oversaw some of Moscow's most damaging Cold War spies in the West -- Klaus Fuchs and the Rosenbergs -- died Friday after a lifetime of espionage that helped the Soviet Union acquire the nuclear bomb.

Alexander Feklisov, who also played a key role as a mediator in the Cuban missile crisis, was 93.

Feklisov arrived in New York in 1941 and began overseeing Julius and Ethel Rosenberg, a married couple who supplied the Soviet Union with top secret information on the U.S. Manhattan project to develop the nuclear bomb.

Feklisov later called the Rosenberg network one of the greatest in the history of Soviet espionage. The Rosenbergs were executed in 1953. "Feklisov made an important contribution to the activity of Russia's foreign intelligence network in New York on nuclear issues," said a spokesman for the Foreign Intelligence Service, or SVR. "He conducted serious missions related to the procurement of secret scientific and technical information, including in the area of electronics, radiolocation and jet aircraft technology," he said, Interfax reported.

In his autobiography, "The Man Behind the Rosenbergs," Feklisov recounted how he had played Le Carre-style espionage games to throw off U.S. minders in New York. He said he oversaw a total of 17 foreign agents.

After working with the Rosenbergs, Feklisov returned as a silent hero to Moscow. But he was quickly dispatched to London in 1947 as deputy chief of intelligence operations for science and technology. He soon made contact -- in a London pub -- with Fuchs, a German-born scientist who worked at the U.S. nuclear bomb project in Los Alamos and at Britain's Harwell nuclear research laboratory. Fuchs passed on secrets that helped speed Moscow's race for the nuclear bomb by at least 18 months, intelligence officials said later when the extent of Fuchs' treason was examined.

"Feklisov was in contact with Klaus Fuchs, who provided important nuclear information, including on the structure of the hydrogen bomb," the SVR spokesman said.

Fuchs served a 14-year sentence for treason after admitting to passing nuclear secrets to Moscow.

Feklisov later called him the most important spy the Soviet Union ever had in its race for the bomb and said the information he gleaned from Fuchs was translated specially for Stalin.

The Soviet Union exploded its first nuclear bomb in 1949, striking fear into the world and surprising Western intelligence, who believed they were at least five years away.

Feklisov returned to the United States to head Soviet intelligence operations in Washington from 1960 to 1964.

As the KGB resident, Feklisov played a key role as a behind-the-scenes intermediary between the Kremlin and Washington in the 1962 Cuban missile crisis, widely seen as the closest the world ever came to nuclear war.

Funeral arrangements were not immediately known.