New files have claimed the Soviet Union feared a missile strike in the wake of the assassination of John F. Kennedy.
Thousands of documents were made public by Donald Trump on Thursday revealing details about the events.
Following the president's death, a memo says the USSR - which comprised Russia and a string of satellite communist states - feared an "irresponsible" general would launch a strike because of a lack of leadership.
The papers say the Soviets also believed the actions of Lee Harvey Oswald - who shot Kenndy on November 22, 1963 in Dallas - were attempts by elements within the United States to stage a coup.
Among the details revealed by the release were a meeting Oswald had with a KGB operative, two months before he killed Kennedy, and Dallas police knew about the threat to kill the young man.
Oswald was later shot dead by nightclub owner Jack Ruby as he was being taken to jail, a moment which was seen by millions of Americans after it was unintentionally televised.
More documents were planned to be released by the US President, but he bowed to pressure from both the CIA and FBI and said no more would be made public until a review was held.