Harvard law professor Alan Dershowitz called reports that President Trump revealed highly classified information to Russian officials “the most serious charge ever made against a sitting president.”

In a discussion on CNN’s “Erin Burnett OutFront” Monday night, Dershowitz said “everything else is off the table” after The Washington Post reported Monday that the president divulged to Russian officials details about the Islamic State in Iraq and Syria’s threat to use laptop computers as bombs on planes.

A U.S. official with knowledge of Trump’s meeting last week with the Russian ambassador and foreign minister said Trump shared “code-word information” and “revealed more information to the Russian ambassador than we have shared with our own allies.”

“Let’s not minimize it,” said Dershowitz, who is a contributor for The Hill.

{mosads}Former FBI Director James “Comey is in the wastebasket of history. Everything else is off the table. This is the most serious charge ever made against a sitting president of the United States. Let’s not underestimate it.”

Dershowitz acknowledged that the president’s alleged actions are not likely illegal, because the president has the authority to declassify information.

“You’re saying this is the most serious charge ever made against a sitting president and yet it’s not criminal, it’s not impeachable, and yet it’s more serious than things that were?” asked CNN’s Burnett.

“Absolutely right,” he responded.

Dershowitz reiterated his claim in a later interview with CNN’s Anderson Cooper, adding, “This is most serious accusation ever made against a sitting president, relating to national security, if it’s true.”

Dershowitz: If true, it’s most serious accusation ever made against a sitting President, relating to nat’l. security https://t.co/Fws8vHK0AJ

— CNN (@CNN) May 16, 2017