President Trump claimed on Tuesday to know the identity of the anonymous White House insider who penned a blistering tell-all about the administration — but refused to divulge the name.

“I know who it is,” Trump told reporters shortly before boarding Air Force One, bound from Joint Base Andrews in Maryland to California.

But pressed for the identity of the insider — known around the Beltway by the nom de plume “Anonymous” — Trump demurred.

“I can’t tell you that,” he said. “But I know who it is.

“I know all about ‘Anonymous,'” the president continued. “I know a lot about the [White House] leakers too.”

Anonymous in 2018 penned an op-ed for the New York Times blasting the president and claiming to be part of a “quiet resistance” working in the White House to undermine Trump.

Trump in turn demanded that the Times name the author — identified in the article only as a “senior official in the Trump administration” — and slammed the mole as “GUTLESS.”

Last year, Anonymous re-surfaced with a warts-and-all book about the administration called “A Warning,” prompting renewed speculation as to their identity.

A former speechwriter for President Clinton speculated that the culprit was Guy Snodgrass, the chief speechwriter for former Defense Secretary James Mattis, but Snodgrass flatly denied the claim.

Asked whether the person he believes to be Anonymous still works in the White House, Trump again declined to elaborate, saying only, “We know a lot.”

With Post Wires