Most of the President John F. Kennedy Assassination Records Collection, which is currently stored at the National Archives, has been released previously. Under 1992’s JFK Assassination Records Collection Act, Congress had approved the declassification of the remainder of these documents by October 27, 2017—unless the sitting president authorized further withholding of files.

President Trump, somewhat of a conspiracy theorist himself, has opted to keep some of these files classified, pending a review which is set to take 180 days. The White House has told reporters that intelligence agencies including the FBI and CIA have requested that the records remain secret.

That the president has opted to withhold some of the documents should come as no surprise. When he first announced that he would allow the files to be released on Saturday, he noted that it was “subject to the receipt of further information.” The president then teased the release of the JFK files via his Twitter account on Wednesday afternoon.

The long anticipated release of the #JFKFiles will take place tomorrow. So interesting!

— Donald J. Trump (@realDonaldTrump) October 25, 2017

The remaining files that were set to be released Thursday were not expected to contain any major revelations. “While NARA cannot comment on the content of the records,” says a National Archives Q&A, “we assume that much of what will be released will be tangential to the assassination events.”

Some experts think the documents could shed light on a trip by Oswald to Mexico prior to Kennedy’s shooting, where the assassin is said to have met with Cuban and Soviet spies and said he wanted to kill the president. There is also speculation that some of the files were amassed in the 1990s, which could have contributed to them being withheld by the government, because they could compromise intelligence gathering techniques or national security.

The October 2017 batch of JFK assassination documents are now available for download from the National Archive’s website.