Donald Trump revealed classified information to the Russian foreign minister and ambassador in a closed-door meeting in the Oval Office last week, officials told the Washington Post.

Trump’s meeting with Russian Foreign Minister Sergei Lavrov and Ambassador Sergey Kislyak—which drew scrutiny after members of the U.S. press were barred from taking pictures—occurred just one day after the president fired former FBI director James Comey, who was leading the investigation into possible collusion between the Trump campaign and Russian operatives.

As the Post reports, the president revealed information obtained from a U.S. ally that exposed an intelligence stream related to the Islamic State. Among the aspects Trump discussed pertained to a specific ISIS plot, as well as the city under ISIS control where the key intelligence ally obtained the information.

“It is all kind of shocking,” a former senior U.S. official told the Post. “Trump seems to be very reckless and doesn’t grasp the gravity of the things he’s dealing with, especially when it comes to intelligence and national security. And it’s all clouded because of this problem he has with Russia."

“This is code-word information,” another  official told the Post, adding the president “revealed more information to the Russian ambassador than we have shared with our own allies.”

Trump's national security adviser H.R. McMaster denied Trump revealed "sources or methods," but made no mention of allegation she disclosed classified information.

“At no time were any intelligence sources or methods discussed, and no military operations were disclosed that were not already known publicly," McMaster said.