US President Donald Trump shakes hands with North Korea's leader Kim Jong Un before in Hanoi on February 27, 2019
CNN  — 

The National Archives alerted lawyers for former President Donald Trump in May 2021 that Trump’s letters with North Korean Leader Kim Jong Un – and two dozen boxes of records – were missing, according to new correspondence the Archives released on Monday.

Gary Stern, general counsel for the National Archives and Records Administration, wrote to former Trump White House lawyers Patrick Philbin, Mike Purpura and Scott Gast on May 6, 2021, alerting them that the letters Trump had exchanged with Kim and the letter he received from his predecessor, President Barack Obama, were missing, according to the correspondence released Monday in response to dozens of Freedom of Information Act requests.

In the email, Stern asked for the lawyers’ help to ensure the Archives received all presidential records as required under law.

“It is also our understanding that roughly two dozen boxes of original Presidential records were kept in the Residence of the White House over the course of President Trump’s last year in office and have not been transferred to NARA, despite a determination by Pat Cipollone in the final days of the Administration that they need to be,” Stern wrote. “I had also raised this concern with Scott during the final weeks.”

CNN previously reported that the Archives had been working throughout 2021 to get presidential records from Trump.

The correspondence released Monday provides additional detail showing how the Archives engaged with Trump’s team for months before he handed over 15 boxes of materials in January that had been housed at Trump’s Mar-a-Lago resort.

In the May 2021 letter to Trump’s representatives that was released publicly on Monday, Stern wrote there were “certain paper/textual records we cannot account for,” citing Trump’s letters with Kim and from Obama.

“For example, the original correspondence between President Trump and North Korean Leader Kim Jong-un were not transferred to us; it is our understanding that in January 2021, just prior to the end of the Administration, the originals were put in a binder for the President, but were never returned to the Office of Records Management for transfer to NARA,” he wrote.

Stern added that the Obama letter was also missing, noting that the Archives’ presidential libraries of other presidents maintain copies of similar letters. “It is necessary that this one be provided to us as well,” he wrote.

The Archives noted it was also seeking to obtain electronic records from the Trump administration. On Friday, the Archives said in a letter to the House Oversight Committee that it still did not have all required records from the Trump administration because officials used personal emails to conduct official government business and did not turn those over as required under the law.

The documents Trump handed over earlier this year included numerous classified documents, which prompted the Archives to refer the matter to the Justice Department.

But the Archives withheld the vast majority of correspondence from public release – more than 1,000 pages worth – citing exemptions to FOIA, including ongoing Justice Department investigations and the Archives’ own deliberations with Trump’s representatives.

In a letter to American Oversight, one of the groups seeking records from the Archives, the agency wrote that it located 309 pages of records related to correspondence with Trump representatives through March 31, 2022. The Archives released 11 pages and withheld 298 pages, including 295 pages the agency said was withheld due to potential interference with law enforcement.

The Archives also identified 1,303 pages of emails between Archives officials and other entities, like congressional offices. The agency released 54 pages from that cache, including correspondence with the House Oversight Committee, while it withheld 1,249 pages, citing its own deliberations and 1,073 pages due to law enforcement.

The National Archives had previously said at least 15 boxes of White House records were recovered from Trump’s Mar-a-Lago resort in January – including some that were classified. And in its August 8 search, the FBI recovered 11 sets of classified documents, including some materials marked as “top secret/SCI” – one of the highest levels of classification.

Soon after that batch of documents was recovered, Trump instructed one of his lawyers to tell the agency that all of the materials they had requested had been returned from his Mar-a-Lago estate, according to multiple sources familiar with the matter.

The former Trump Organization attorney, Alex Cannon, had been working with Archives representatives since 2021 to facilitate the return of records that had been taken to Trump’s Florida residence at the end of his presidency.

Because Cannon was based in New York and had been assisting with the records matter from afar, he was unsure whether the Archives had received everything in Trump’s possession and thus refused the former President’s request, said people familiar with the matter. Trump told Cannon not to involve himself further, the sources said.

The Washington Post reported first reported on Cannon’s refusal.

This story has been updated with additional details.

CNN’s Kaanita Iyer contributed to this report.