According to The New York Times, the US government got over 300 classified documents from Trump.
The National Archives spent a lot of time trying to get their hands on property.
The items were described as "mine" by Trump, who refused to return them.
The New York Times reported Monday that the National Archives and Records Administration spent more than a year trying to get back official materials from Donald Trump's presidency.
The National Archives spent a lot of time trying to recover the two dozen boxes of presidential records that were moved from the Oval Office to the White House residence.
All official materials must be handed over to the National Archives when a president leaves office, according to the Presidential Records Act.
According to The Times, two former White House officials who were tasked with representing the former president tried to get the documents back.
Three advisers told the outlet that Trump called the boxes of documents "mine".
The National Archives wanted to take back Trump's original letters with Kim and the note Obama left Trump before he was inaugurated, The Times reported.
The FBI raided Trump's Mar-a-Lago resort earlier this month and seized 26 boxes of documents, one of which had the highest security classification.
More than 300 classified documents were retrieved from Trump by the government, according to the Times. The former president returned the first set in January, his Justice Department aides delivered a second set in June, and the FBI claimed more material in the raid.
It's not known how these documents are traditionally stored in the White House or how they should be stored in the National Archives, but several people familiar with the investigation told The Times that the FBI found documents in a container that was in a closet in Trump's office.
A representative with the Justice Department didn't reply to Insider's request for comment.
Business Insider has an article on it.