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

The National Archives posted another 676 records related to President John F. Kennedy’s assassination Friday afternoon, including more than 500 never-before-seen CIA files that contain information about Lee Harvey Oswald and operatives-turned-Watergate burglars James McCord and E. Howard Hunt.

One of the CIA files details Oswald’s visits to the Cuban consulate and Soviet embassy in Mexico City in the weeks before he fatally shot Kennedy on Nov. 22, 1963 in Dallas. Oswald himself was shot by nightclub owner Jack Ruby in Dallas police headquarters on live television, fueling decades of conspiracy theories about the assassination.

How much did the CIA know about Oswald’s intentions before the assassination?

Jefferson Morley, one of a handful of experts who has closely tracked the Kennedy records for many years, believes one of the more interesting documents to emerge involves a CIA cable about Oswald’s contacts in Mexico City that had up until Friday been partially redacted. The Oct. 8, 1963 cable discussed Oswald’s interactions with a Soviet consular official named Valery Kostikov, the reputed head of the KGB’s assassinations operations. On Friday, the CIA cable’s slugline was finally declassified. The title: LCIMPROVE.

LCIMPROVE was the CIA’s code name for counter-espionage involving the Soviet intelligence services. The agency’s man in charge of LCIMPROVE? James Jesus Angleton, the CIA’s legendary chief of counterintelligence.

To Morley, the author of a new biography on Angleton published in late October, this meant one thing:

“What the Mexico City cable illuminates is the failure of a senior CIA official to preempt Oswald as he made his way to Dallas,” Morley wrote on his web site, JFKFacts.org. “Now we know that Angleton also knew Oswald had been in contact with a KGB officer who some said was a KGB assassin. After receiving the October 8 cable, Angleton could have asked the FBI to locate and interview Oswald to explain his contacts with Kostikov. The FBI located him but Angleton is not known to have taken any action.”

Other previously secret CIA files reveal the “involuntary” 1970 retirement of McCord and Hunt’s frustration with being consigned to a desk job after covert anti-Castro operations.

The Post's Ian Shapira explains why three documents from the trove released by the National Archives related to the assassination of President John F. Kennedy are of particular interest. (Claritza Jimenez/The Washington Post)

The latest document dump was 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. In the days leading up to the deadline, President Trump announced on Twitter that he was allowing “the long blocked and classified JFK FILES to be opened.” But on Oct. 26, Trump bowed to pressure from the CIA, FBI and other agencies by releasing only 2,800 records and withholding 30,000 others. Trump issued a memo saying he would delay making a decision on those files until April 26.

But over the next two days, Trump issued a series of tweets that suggested he wanted to release the remaining documents much sooner. “After strict consultation with General Kelly, the CIA and other Agencies, I will be releasing ALL #JFKFILES other than the names and addresses of any mentioned person who is still living. I am doing this for reasons of full disclosure, transparency and . . . in order to put any and all conspiracy theories to rest.”

Trump himself floated a conspiracy theory during the presidential campaign in 2016 that the father of his primary opponent, Sen. Ted Cruz (R-Texas), was somehow involved in the assassination.

So far, there have been no bombshells in the new files released, and experts did not expect any to shake the conclusion of the Warren Commission that Oswald acted as the lone gunman in Dealey Plaza. A majority of Americans believe others were involved, according to several Gallup polls taken over the years. And some Kennedy experts and historians have concluded that the CIA and other intelligence agencies impeded the Warren Commission’s investigation.

One long withheld FBI file released Friday is a March 12, 1968 analysis of civil rights leader Martin Luther King Jr., whom former director J. Edgar Hoover had long sought to discredit. It includes salacious details about wild parties and sexual indiscretions by King, who was assassinated just weeks later.

Other records include hundreds of pages on the Watergate burglars, including some CIA internal papers praising the skills that would later be used in the infamous 1972 break-in. It wasn’t clear why McCord’s retirement from the agency was labeled “involuntary.”

“In a variety of assignments, both domestic and abroad, Mr. McCord has displayed unusual imagination, ingenuity, and effectiveness in accomplishing his assigned tasks,” wrote one CIA official of the man who would, two years later, use those skills to break into the National Democratic Party’s headquarters in the Watergate. “His achievements in the fields of audio-countermeasure techniques and physical and technical security are particularly noteworthy…”

Then-CIA director Richard Helms wrote to McCord to commend him and wish him a happy retirement “filled with enjoyment and satisfaction.”

“Your faithful and loyal support has measured up to the high ideals and traditions of the Federal service,” he wrote.

McCord even got an award: the Certificate of Distinction for his 20 years of service.

Three years later, a jury took just 90 minutes to convict McCord of eight counts, including conspiracy, burglary and wiretapping the Democrats.

In a January 1965 CIA file, E. Howard Hunt complained that he had developed a duodenal ulcer from tedious assignments following the excitement of anti-Castro operations, known as Project JMATE, that culminated in the Bay of Pigs invasion.

The ulcer, he wrote, resulted from “three years of work frustration and professional dissatisfactions occasioned by (a) Agency failure to assign me to an appropriate post abroad following my participation in Project JMATE, and (b) the passive, non-challenging nature of the domestic work I was given.”

Hunt had hit a “professional dead-end,” he wrote, “without hope of promotion or foreign assignment, a situation which preoccupied my mind and in due course found physical reflection in duodenal hemorrhage.”

A 1969 fitness report by Hunt’s boss, the CIA’s chief of operations in Europe, concluded that Hunt was “a very competent, tough-minded senior professional.” But a “reviewing officer’s comment” attached to his fitness report recommends that his overall performance be rated as “highly proficient” rather than “strong” because “this officer has had a series of personal and taxing problems, beyond his control, which have tended to dull his cutting edge just enough to be noticeable.”

Hunt retired in 1970 and later organized the Watergate break-in and dirty tricks that ultimately brought down the Nixon presidency. He was convicted of burglary, conspiracy and wiretapping and served 33 months in prison.

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