The revelation that federal prosecutors have a recording of former President Donald J. Trump discussing a highly sensitive document in his possession after he left office underscores the weight of the evidence that the special counsel Jack Smith is assembling as he approaches a decision about whether to bring criminal charges.
The recording, according to people briefed on its contents, captured Mr. Trump in July 2021 discussing a document that he said related to military planning for confronting Iran. During the conversation, Mr. Trump signaled his awareness of his inability to declassify the document because he had already left office, they said.
If that description of the recording proves correct — and Mr. Trump’s lawyers have been careful not to confirm or deny it — it would undercut one of the key defenses that Mr. Trump’s advisers have offered in their effort to justify why he was allowed to hold onto some of the government’s most sensitive secrets after leaving the White House. They have argued that Mr. Trump, while still in office, had declassified all the material he took with him when he left.
It would also show Mr. Trump, in his own voice, invoking a sensitive government document to settle a score. In this case, he was rebutting what he perceived as criticism from Gen. Mark A. Milley, whom Mr. Trump appointed as the chairman of the Joint Chiefs of Staff.
The precise contents of the document referred to by Mr. Trump during the recorded meeting remain unclear. And it is not known when or whether the federal government recovered the document from Mr. Trump as it sought to retrieve thousands of pages of material he took with him when he moved out of the White House in violation of the Presidential Records Act. That act makes all presidential records the property of the federal government.
But a recording demonstrating that he knew he had material that he had not declassified — and that it touched on highly sensitive national security issues — could potentially be compelling evidence that he was aware he should not have kept it even as federal officials were stepping up their efforts to recover what he had taken with him.
The federal prosecutors under Mr. Smith have been examining whether Mr. Trump — the front-runner for the 2024 Republican presidential nomination — obstructed the government’s efforts and whether he violated other laws regarding the handling of national defense information and government documents. Mr. Smith is also overseeing a parallel investigation into Mr. Trump’s efforts to remain in office after his defeat at the polls in 2020.
After months of back-and-forth with the National Archives, Mr. Trump eventually turned over 15 boxes of material in January of last year. They turned out to include nearly 200 documents marked as classified.
After a subsequent subpoena demanding that he return any other classified material in his possession, he gave the Justice Department a little over three dozen additional documents and a letter from his lawyer saying that a diligent search had turned up nothing more.
Then, in August, F.B.I. agents with a search warrant swooped down on Mar-a-Lago, his residence and club in Florida, and carted away additional boxloads of material, with more than 100 additional classified documents.
The meeting that was recorded was more than a year before the search and was between Mr. Trump and two people helping with a book being written by the final Trump White House chief of staff, Mark Meadows, according to three people familiar with the session. A small number of Trump aides, including Margo Martin, who routinely sat in on and recorded book interviews granted by Mr. Trump, were present as well.
Ms. Martin was subpoenaed to appear before the grand jury hearing evidence in the case in March. According to a person familiar with the situation, investigators had the recording of the meeting before Ms. Martin’s appearance. Her devices were subpoenaed after the appearance, the person said.
Some of Mr. Trump’s own advisers, aware of the recording’s existence, have been waiting for it to become public since Mr. Trump’s town hall event on CNN in May, during which he gave an equivocating answer when asked directly if he had ever shown any classified documents to people after leaving the White House. “Not really,” Mr. Trump said.
A lawyer for Mr. Trump continued to take the position, in an interview on CNN on Wednesday, that his client had declassified the materials he removed from the White House and could prove it.
But even the lawyer, James Trusty, refused to say whether Mr. Trump had declassified the document he waved around at the July 2021 meeting that took place at his private club in Bedminster, N.J.
In a separate interview on CNN on Thursday, a lawyer who recently left Mr. Trump’s team, Timothy Parlatore, downplayed the legal significance of the episode at Bedminster and suggested that Mr. Trump had the documents because of a “failure of process” when he left the White House.
Mr. Parlatore said the question of whether the documents had been declassified was not relevant because Mr. Trump was being investigated for “willful retention of national defense information” under statutes that did not depend on classification status.
During the summer of 2021, Mr. Trump was infuriated at General Milley’s high-profile roles in books and magazine articles. General Milley was portrayed as a last line of defense against an increasingly erratic and bellicose president in his final months in office. On the tape, Mr. Trump hit back at General Milley, according to the people familiar with its contents. He suggested that it was General Milley — and not himself — who was a dangerous warmonger. He indicated he had a document that showed General Milley wanted to go to war with Iran.
Former senior government officials who were involved in Mr. Trump’s Iran deliberations said General Milley typically urged restraint against Iran. They said they knew of no document drafted by the chairman of the Joint Chiefs that matched the description suggested by Mr. Trump.
These former officials, who spoke on the condition of anonymity to describe sensitive discussions, said Mr. Trump could have been referring to summaries of deterrence options — ranging from fairly benign to highly aggressive — that were presented to him as he considered how to counter Iran.
Mr. Smith and his team have been exploring the documents case from multiple angles, including examining whether there are links between the material Mr. Trump took and his foreign business deals. They are also scrutinizing whether his employees sought to interfere with the government’s attempt to obtain security camera footage from Mar-a-Lago.
But the existence of the recording opens up new questions, including what role Mr. Meadows might be playing in providing information to investigators, and highlights the extraordinary sensitivity of the material that Mr. Trump had access to as he was leaving office.
Mr. Meadows has for months been a source of suspicion and frustration among some in Mr. Trump’s orbit. Mr. Trump was infuriated by Mr. Meadows’s memoir, which revealed intimate details of the former president’s bout with Covid in 2020. Mr. Meadows then provided something of a road map to investigators when he handed over thousands of private text messages to the House select committee investigating the Jan. 6 attack on the Capitol, leaving out only those that he believed to be protected by executive privilege.
But until now, Mr. Meadows’s publicly known role in the investigations related to Mr. Trump had been mostly restricted to taking part in an expansive effort to limit the scope of the grand juries investigating his former boss with assertions of various kinds of privilege.
A lawyer for Mr. Meadows, George Terwilliger, declined to comment.