Washington DC - The US National Archives on Tuesday released the final batch of files related to the assassination of the late President John F. Kennedy.

The move follows an executive order issued by President Donald Trump in January directing the unredacted release of the remaining files related to the assassinations of Kennedy, his brother, former attorney general Robert F. Kennedy, and civil rights leader Martin Luther King Jr.

"In accordance with President Donald Trump's directive... all records previously withheld for classification that are part of the President John F. Kennedy Assassination Records Collection are released," the Archives said in a statement on its website Tuesday evening.

The National Archives has released millions of pages of records over the past decades relating to the assassination of then-president Kennedy in November 1963, but thousands of documents had been held back at the request of the Central Intelligence Agency and Federal Bureau of Investigation, citing national security concerns.

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The Warren Commission that investigated the shooting of the 46-year-old president determined that it was carried out by a former Marine sharpshooter, Lee Harvey Oswald, acting alone.

But that formal conclusion has done little to quell speculation that a more sinister plot was behind Kennedy's murder in Dallas, Texas, and the slow release of the government files has added fuel to suspicions.

Oswald was shot by a strip club owner, Jack Ruby, on November 24, 1963 -- two days after Kennedy's killing – while being moved to a county jail.

Many of the records already released were raw intelligence, including scores of reports from FBI agents following up leads that led nowhere.

Much of what they contain was also previously known, such as the communist-obsessed CIA cooking up several outlandish plots to murder Cuba's Fidel Castro.

Oswald defected to the Soviet Union in 1959 but returned to the US in 1962.