President John F. Kennedy, left, in 1962, and his assassin, Lee Harvey Oswald, on his way to being interrogated on Nov. 23, 1963. (Photos by Associated Press)

The National Archives posted another huge trove of records related to the John F. Kennedy assassination Thursday, though nearly all of the 13,000 files are previously released documents that apparently contain fewer redactions.

It was not immediately clear how much new declassified material is contained in Thursday’s release. A small number of records related to the president’s murder by Lee Harvey Oswald on Nov. 22, 1963, appear to be entirely new.

One top-secret NSA document from December 12, 1963 – which still had blanked-out sections – contains a memo reporting that the Cambodian government was encouraging its people to celebrate JFK’s death.

Another new record appears to be an NSA report on Britain’s reaction to the assassination. According to a top-secret “dinar” — a report relying on intercepted communications — Britons were wary of what Lyndon B. Johnson would do on the world stage.

While “some circles in Britain believe that Johnson is an astute politician who is skillful in figuring and evaluating and a conservative who is practiced in conducting a policy of conciliation,” the report said, others “think it possible that [Soviet Premier Nikita] Khrushchev will have no confidence in him and that [French President Charles] De Gaulle may seize the opportunity to activate his plans in Europe.”

The report also notes Johnson’s ties to “oilmen in Texas” and “top men of the armed forces.” It recommends the NSA maneuver the new president away from the agency’s “opponents” within the U.S. government.

“It would appear that our opponents will try at the first opportunity to complicate matters between us and the new administration,” the report warned, “by exploiting: the situation in Yemen; or the Algerian-Moroccan dispute and our position toward it; or the Arab-Israeli dispute if they find a chance to raise it; etc.”

On Twitter, Larry Sabato, the director of the University of Virginia’s Center for Politics and the author of a book about Kennedy’s legacy and assassination, highlighted some of his discoveries in the files. One memo from late November 1963 sent to the NSA discussed a plot to kill Kennedy and one of his sisters. The memo is not entirely straightforward, but Sabato believes the potential assassin was code-named CRITIC.

“Some time ago, this center received a CRITIC, during one of the President’s Kennedy’s trips to Florida, regarding a plot to assassinate the President and his sister,” the memo said. “(This CRITIC is not on file in this headquarters…) In view of recent events and accused slayed Oswald’s purported Cuban associations it is recommended that intercept records be researched to determine a possible connection between cited CRITIC and and the slaying of President Kennedy.”

Sabato also was intrigued by a NSA memo, written about a week after the assassination, summarizing Cuban leader Fidel Castro’s reaction to Kennedy’s death.

“Contradictions show that Oswald was made the culprit by the police or was prepared to commit the act with promise of escape, and was assigned activities so as to have responsibility fall on or be insinuated against those whom the perpetrators wished,” Castro said. “It is clear that United States reactionaries tried to make Cuba and the world the victims of their criminal designs, even at the price of assassinating their own president.”

But the Virginia professor also expressed frustration that at least one of the previously released documents was still filled with redactions.

One CIA document released in the late 1990s summarizing an intercepted phone call Oswald made to the Soviet Embassy in Mexico City included this blanked-out sentence: “This piece of information was produced from [REDACTED]. It is highly secret [REDACTED].”

In the version of that record released on Thursday, the passage now adds one word — “a” — and a second sentence that is also redacted: “This piece of information was produced from a [REDACTED]. It is highly secret and not known to [REDACTED] who have their own center.”

The National Archives’ disclosure is the third since late October and the fourth this year. The document dumps have been set in motion by the President John F. Kennedy Assassination Records Collection Act of 1992, which stipulated that the government had to release all remaining assassination records by Oct. 26, 2017. Only the president had the authority to extend the deadline for national security reasons.

Initially, President Trump announced on Twitter that “the long blocked and classified JFK FILES” would be released by the deadline. But on Oct. 26, he bowed to pressure from the CIA, FBI and other agencies by releasing only 2,800 records and withholding 30,000 others. Then, over the next two days, Trump issued tweets suggesting that he wanted to release the remaining documents as soon as possible “to put any and all conspiracy theories to rest.”

On Nov. 3, the National Archives posted another 676 documents, including more than 500 records of new material from the CIA that contained information on Oswald, CIA-operatives-turned-Watergate-burglars E. Howard Hunt and James McCord, and Martin Luther King Jr.

The Warren Commission concluded that Oswald, a former Marine who once defected to the Soviet Union, acted as the lone gunman in Dealey Plaza. Two days later, Oswald was shot and killed by Dallas nightclub owner Jack Ruby on live television, fueling conspiracy theories about  whether he acted alone. Indeed, Gallup polls over the past several decades repeatedly show that most Americans believe that others were involved in the killing somehow.

Read more Retropolis:

Zapruder captured JFK’s assassination in riveting detail, fueling decades of conspiracy theories

JFK assassination conspiracy theories: The grassy knoll, Umbrella Man, LBJ and Ted Cruz’s dad

Lee Harvey Oswald’s eerie calm the day before he pulled the trigger

‘Foul traitor’: New JFK assassination records reveal KGB defector’s 3-year interrogation

JFK’s last birthday: Gifts, champagne and wandering hands on the presidential yacht