WASHINGTON (NewsNation) — The U.S. National Archives on Thursday released thousands of documents related to the assassination of President John F. Kennedy in 1963.

The release of the 13,173 documents came shortly after President Joe Biden issued an executive order authorizing the release that also kept hundreds of other sensitive records secret.

While it is a significant release of some of the most sensitive materials surrounding Kennedy’s assassination, some still are being kept under wraps — at least for now.

According to the White House, the roughly five million pages of released documents mean that 97% of the JFK records are now unsealed.

Thursday’s release shines a light on what the CIA may have known about Lee Harvey Oswald ahead of Kennedy’s death, such as the agency’s surveillance of Oswald during his visit to Mexico City just weeks before the assassination.

The agency reportedly intercepted a call between Oswald and the Soviet Embassy. In the call, Oswald — who was speaking in broken Russian — referred to a previous meeting he had with an embassy official, then asked if there was “anything new.”

Earlier releases revealed Oswald had made contact with Soviet and Cuban spies, including a KGB assassin, while in Mexico.

U.S. agencies kept tabs on Oswald for the three years before Kennedy’s murder, which was also around the time when Oswald tried to return to the U.S. from the Soviet Union. Other documents reveal Oswald was rejected by the KGB because he was considered to be too mentally unstable.

The Warren Commission, established by President Lyndon B. Johnson, concluded that Oswald acted alone. That probe has been widely criticized by academics and historians in the nearly 60 years since the assassination.

As for Jack Ruby, the nightclub owner and alleged associate of the Chicago Outfit who shot and killed Oswald on live television while he was in police custody, one document released Thursday said the CIA found “no indication that Ruby and Lee Harvey Oswald ever knew each other.”

Even with Thursday’s release, more than 3,000 documents are still under wraps decades after Kennedy’s fatal motorcade shooting in Dallas’s Dealy Plaza.

The Biden administration said he agreed to postpone the additional release to “protect against an identifiable harm to the military defense, intelligence operations, law enforcement, or the conduct of foreign relations that is of such gravity that it outweighs the public interest in disclosure.”

Agencies now have until May of 2023 to review the remaining documents and make a decision on whether they should remain secret. If those meet narrow exceptions, they are set to be released by June 30, 2023.

In 1992, Congress ordered that all remaining sealed files pertaining to the investigation into Kennedy’s death should be fully opened to the public through the National Archives in 25 years, by Oct. 26, 2017, except for those the president authorized for further withholding.

Reuters contributed to this story.