JFK files: 10 things the previously classified papers reveal

The killing of US President John F Kennedy still fascinates the public 54 years on.

The official Warren Commission report, which declared former marine Lee Harvey Oswald acted alone, continues to face heavy scepticism from conspiracy theorists.

:: Trump delays releasing 'sensitive' JFK files

We take a look at the 2,891 never-seen-before secret files about the assassination to see whether they settle the matter once and for all.

:: British paper was 'tipped off' about assassination

A British newspaper received an anonymous call about "some big news" in America - 25 minutes before President John F Kennedy was assassinated, documents have shown.

A memo to the FBI reads: "The caller said only that the Cambridge News reporter should call the American Embassy in London for some big news and then hung up."

After news of the president's death came through, details of the call were passed on to the police and MI5.

The reporter was not named but was described as "a sound and loyal person with no security record".

:: Soviets feared blame over assassination

Documents from then-FBI director J Edgar Hoover reveal that the Soviet Union feared it would be blamed for putting Lee Harvey Oswald up to assassinating Mr Kennedy - which could have lead to nuclear war.

"As a result of these feelings, the Soviet Union immediately went into a state of national alert," he said.

"Our source further stated that Soviet officials were fearful that without leadership, some irresponsible general in the United States might launch a missile at the Soviet Union."

:: FBI knew about threat to kill Oswald

A threat had been made to kill Oswald the night before he was shot by nightclub owner Jack Ruby.

A memo dictated by Mr Hoover on 24 November 1963, hours after the shooting, started: "There is nothing further on the Oswald case except that he is dead."

He said after Oswald's arrest that he "received a call in our Dallas office from a man talking in a calm voice and saying he was a member of a committee organised to kill Oswald".

The police had assured him Oswald would be protected but this "was not done".

Oswald was murdered as he was being transferred from the city jail, two days after Mr Kennedy's death.

The memo added: "We had an agent at the hospital in the hope that he might make some kind of a confession before he died but he did not do so."

:: 'Hairbrained' CIA plots to kill Fidel Castro

There are also notes and reports that reveal the Kennedy administration's covert efforts to kill Fidel Castro and overthrow his government in Cuba.

A document details elaborate plots including a plan to get poison pills "into the hands of someone who could place them in a beverage to be drunk by Premier Castro" and how the CIA hired an intermediary to approach Mafia boss Sam Giancana to offer him "$150,000 to hire some gunman to go into Cuba and kill Castro".

It also discusses Castro's known love of diving and what are described as "hairbrained" schemes to eliminate the leader, including an exploding seashell and by giving him a contaminated diving suit.

"The CIA plan was to dust the inside of the suit with a fungus producing medera foot, a disabling and chronic skin disease, and also contaminating the suit with tuberculosis bacilli in the breathing apparatus," it read.

"During this period of time there were also discussions about preparing a booby-trap spectacular seashell" which "would be loaded with explosives to blow apart when the shell was lifted".

:: Threats to John F Kennedy

A 400-page document appears to describe people being monitored as potential threats to Kennedy and his successor, Lyndon Johnson.

One suspect is described as a "subject" who "participated in pickets against JFK in 1961".

"Allegedly trained in guerilla tactics & sabotage," it read.

"Considered very dangerous by those who know him. Has visited USA & Cuba. Considered armed and dangerous."

It reveals one person sent a letter to Mr Johnson in December 1963 stating "you're doomed".

It continued: "Interviewed 1/23/64; friendly. Said letter was a joke. Not dangerous. Attending 5th grade."

:: Oswald met with KGB agent

A file reveals Oswald met with a KGB sabotage and assassination officer less than two months before Mr Kennedy was shot and killed in Dallas on 22 November 1963, and that CIA agents speculated he might be a KGB agent.

A document, dated the day after the killing, reveals the CIA intercepted a call Oswald made to a KGB officer - Valeriy Vladimirovich Kostikov - at the Soviet Embassy in Mexico City which he visited on 28 September the same year.

"This was learned when OSWALD called the Soviet Embassy on 1 October, identifying himself by name and speaking broken Russian, stating the above and asking the guard who answered the phone whether there was 'anything new concerning the telegram to Washington'.

"The Guard checked and then told OSWALD that a request had been sent, but nothing had as yet been received," it read.

It added: "We have top secret Soviet intelligence documents, describing military intelligence doctrine, which show that very important agents can be met in official installations using cover for their presence [as if] there [for] some sort of open business."

:: Soviet view of JFK assassination

The Soviets described Lee Harvey Oswald as a "neurotic maniac" and believed Mr Kennedy's assassination was organised by the US right wing.

"They seemed convinced that the assassination was not the deed of one man, but that it arose out of a carefully planned campaign in which several people played a part," said Mr Hoover in a memo to the White House on 1 December 1966.

He added: "According to our source, Soviet officials claimed that Lee Harvey Oswald had no connection whatsoever with the Soviet Union. They described him as a neurotic maniac who was disloyal to his own country and everything else."

:: Soviets claimed they had 'data' Johnson was behind assassination

The KGB thought then-vice president and Mr Kennedy's successor Lyndon Johnson could have been behind the assassination.

In the same December 1966 memo, Mr Hoover notes sources said "the KGB was in possession of data purporting to indicate President Johnson was responsible for the assassination of the late President John F Kennedy".

He also revealed that "it was of extreme importance to the Soviet government to determine precisely what kind of a man the new President Lyndon Johnson would be", adding he was "practically unknown to the Soviet government and, accordingly, the KGB had issued instructions to all of its agents to immediately obtain all data available concerning the incumbent President".

:: Oswald's bus trip to Mexico

An April 1964 FBI document recounts Lee Harvey Oswald's bus trip to Mexico in October 1963, just weeks before the assassination.

It includes the names of the people sitting around him and details he was wearing "a short-sleeved light coloured sport shirt and no coat".

:: Hoover feared spread of JFK conspiracy theories

Mr Hoover vented his frustration over Oswald's death in a memo.

He said he and then-deputy attorney general Nicholas Katzenbach feared the spread of conspiracy theories following Mr Kennedy's assassination, given that the FBI never got a confession to the shooting from the former US marine.

He wrote: "The thing that I am concerned about, and so is Mr Katzenbach, is having something issued so that we can convince the public that Oswald is the real assassin."