"I agree with the Archivist's recommendation that the continued withholdings are necessary to protect against identifiable harm to national security, law enforcement, or foreign affairs that is of such gravity that it outweighs the public interest in immediate disclosure. I am also ordering agencies to re-review each of those redactions over the next 3 years," Trump said in the memo.
Trump's memo coincided with the release on Thursday of 19,045 documents on the Kennedy assassination.
READ MORE: JFK: The Assassination That Shook the World and Continues to Evoke Fierce Debate
The US National Archives and Records Administration (NARA) said in a press release that it released the documents to the public in accordance with the JFK Records Act of 1992, which ordered the NARA to establish a collection of all records pertaining to Kennedy's assassination.
Trump's memo said that if any executive departments or agencies want to keep documents classified after 2021, they must provide an explanation of their reasoning to the Archivist, who will then advise the president on the next steps.
READ MORE: Fifth Batch of JFK Files Released to Public
Under the JFK Records Act, the NARA was required to disclose the entire collection to the public in exactly 25 years, which was on October 26, 2017, unless the US president decided that releasing the information would harm national security or current foreign relations.