In a statement posted on its website, the Kremlin said Putin had posthumously awarded the Gold Star and Hero of Russia medal to George Koval, who died in 2006 at the age of 94.

"Mr. Koval, who operated under the pseudonym Delmar, provided information that helped speed up considerably the time it took for the Soviet Union to develop an atomic bomb of its own," the statement said.

His efforts ensured "the preservation of strategic military parity with the United States."

Koval's identity was not made public until summer this year, a year after his death, the NTV television network said.

The Kremlin statement said Koval had penetrated top-secret US atomic facilities producing the plutonium, enriched uranium and polonium used to create the first atomic bomb.

"Despite the top-secret regime at the facilities and strict control over staff, Mr. Koval managed to send descriptions of the sites back to Moscow, along with information on their areas of work and the processes and production volumes of the elements in question," the Kremlin statement said.

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