Trump is stretching his declassification defense in the Mar-a-Lago case further still, making an argument his lawyers have gone nowhere near in court

• Donald Trump has claimed he declassified documents retrieved by the FBI from Mar-a-Lago.
• Yet neither he nor his lawyers have backed the claim with convincing evidence.

Former President Donald Trump has claimed for weeks that he declassified stashes of highly confidential government documents the FBI retrieved in its August 8 search of his Mar-a-Lago resort.

The claim has been his chief argument in defense of accusations he mishandled the information and imperiled US national security. But the claim is coming under increasing pressure.

Trump has so far provided no evidence to back his claim, with documents clearly marked "classified" photographed strewn among his personal effects in a DOJ legal filing.

And in an interview with Fox News host Sean Hannity on Wednesday, Trump stretched the plausibility of the defense even further, asserting that he had the power to declassify information simply by thinking about it.

"There doesn't have to be a process, as I understand it," Trump said. "You're the president of the United States, you can declassify just by saying it's declassified, even by thinking about it."

National security attorney Bradley P. Moss said that while technically the president does have unfettered power to declassify information, specific procedures must be followed and that relevant government agencies must be notified.

He told Insider that the government and courts had concluded that "presidential assertions of declassification do not become effective unless there is subsequent follow up to actually implement the order."

Trump's lawyers, who are engaged in a legal battle over the documents, are also refusing to provide evidence to back Trump's claim.

In a court appearance Tuesday, special master Raymond Dearie, the official assigned to review the documents, pushed Trump's lawyers to provide evidence for the declassification claim.

But Trump's lawyers didn't, arguing that making the evidence public could damage their defense if the case came to trial.

"As far as I'm concerned, that's the end of it," Dearie said, indicating that he was losing patience with the declassification claim. "You can't have your cake and eat it."

The refusal to back the claim with evidence is striking, and hints at the legal peril facing Trump.

Trump's lawyers are seeking to retrieve some of the documents taken from Mar-a-Lago under rules shielding private presidential communications from public scrutiny, or "executive privilege" rules.

But executive-privilege rules cannot be used to shield classified information and other government records of the kind retrieved by the FBI, Michael Stern, a former counsel for the US House of Representatives, recently told Insider.

Moss added that even if Trump had followed the correct declassification procedures, the laws he is suspected by the DOJ of having violated do not hinge on the documents being classified,

"The declassification argument is ultimately irrelevant to any Espionage Act charge, at least as a matter of law," he said.

In a ruling Wednesday, an Atlanta appeals court reinstated the DOJ's access to the classified information, and dismissed the declassification argument as a "red herring" that did not exculpate Trump even if true.

"The declassification argument is a red herring because declassifying an official document would not change its content or render it personal," the ruling said, adding that Trump had not even "attempted to show" he has an individual or personal interest in the classified documents.