The National Archives published nearly 3,000 previously sealed or censored documents related to the assassination of President John F. Kennedy on Thursday, but the White House said it was delaying the release of others.

Under a 1992 law inspired by the conspiracist movie "JFK," the National Archives was supposed to have released all of the remaining records by midnight ET — unless President Donald Trump objected on national security grounds.

In the end, the president allowed the release of 2,891 of at least 3,140 documents, with the rest subject to a 180-day review of redactions from objecting agencies. The White House said later that the remaining records would be released "on a rolling basis in the coming weeks."

"I am ordering today that the veil finally be lifted," Trump wrote in a memo announcing the delay Thursday evening.

"At the same time, executive departments and agencies have proposed to me that certain information should continue to be redacted because of national security, law enforcement, and foreign affairs concerns," he wrote. "I have no choice — today — but to accept those redactions rather than allow potentially irreversible harm to our Nation's security."

Still, he warned that agency heads should be "extremely circumspect" in asking for further postponing the release of any of the documents, saying: "The need for continued protection can only have grown weaker with the passage of time."

President John F. Kennedy's motorcade in Dallas on Nov. 22, 1963. Newseum / PRNewsfoto file

Trump "wants to ensure there is full transparency here," a senior administration official said at a briefing. He is "expecting agencies to do a better job in reducing conflict within redactions and get this information out as quickly as possible."

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The CIA said in a statement that the redactions were meant to protect information that would "harm national security — including the names of CIA assets and current and former CIA officers, as well as specific intelligence methods and partnerships that remain viable to protecting the nation today."

"Every single one of the approximately 18,000 remaining CIA records in the collection will ultimately be released, with no document withheld in full," the agency said.

Trump, no stranger to conspiracy theories about the Kennedy killing, had appeared eager to get the latest JFK documents out.

The long anticipated release of the #JFKFiles will take place tomorrow. So interesting! — Donald J. Trump (@realDonaldTrump) October 25, 2017

As journalists, scholars and assassination buffs began scouring the thousands of pages Thursday night, it remained to be seen whether the document dump would satisfy the many people who still dispute the finding of the Warren Commission that Lee Harvey Oswald acted alone when he gunned down Kennedy on Nov. 22, 1963.

The assassination shocked the nation and spawned a conspiracy industry that continues to pump out alternative theories about who was really behind the killing.

Officials at the National Archives made a point of trying to tamp down expectations that the newest batch of documents contains any blockbuster revelations — and they have noted repeatedly that about 90 percent of the available records related to the assassination are already public.

Related: What Could Be in the New Kennedy Assassination Records?

Clint Hill, the Secret Service agent who used his body to shield the mortally wounded president and first lady Jacqueline Kennedy after the first shots rang out in Dallas, said earlier Thursday that he hoped the latest declassified papers shed light on why Oswald pulled the trigger.

"I'm hoping that within that material — and there's lots of it — there will be some indication as to the motive, the reason why he did what he did," Hill told MSNBC.

Hill said he still blames himself for not having reacted faster when the presidential motorcade came under fire.

"Deep down, I still have that sense of guilt that I should have been able to get there quicker and I didn't," he said. "I was the only one who had a chance to do anything."

The paperwork that was scheduled to be unveiled on Thursday has already been vetted by the Assassination Records Review Board, a panel created in the aftermath of Oliver Stone's 1991 conspiracy film "JFK," which popularized the notion that Kennedy was killed by rogue FBI and CIA agents.

The ARRB released the bulk of the JFK assassination paperwork two years after it was founded. The new documents were marked "NBR," or Not Believed Relevant, the panel's chairman, John Tunheim, said in March at a National Press Club conference in Washington.

"It's not that important to keep protecting it," he said. Still, he added, "I think there will be stuff interesting to researchers."

PHOTOS: JFK Assassination: The Day the President Was Shot

About 200 pages of the new batch are expected to delve into the six-day visit that Oswald, a onetime Marine who had defected to the Soviet Union, made to Mexico City just before Kennedy's assassination. One of the juiciest stories is likely to be that of June Cobb, a CIA spy working in Cuba and Mexico, who reported that Oswald had been spotted in Mexico City.

Cobb, born Viola June Cobb in Ponca City, Oklahoma, died Oct. 17, 2015, in New York, where she was living in a Manhattan senior center, an official there and her former sister-in-law told NBC News.

Tunheim said in March that the CIA, the State Department and other federal agencies balked at releasing the Mexico City paperwork "because it was thought to be detrimental to our relationship with the Mexican government at the time."