President Donald Trump shared highly classified information with the Russian foreign minister and ambassador to the U.S. during an Oval Office meeting last week, jeopardizing the intelligence community’s access to a key source on the Islamic State, the Washington Post reported Monday.

Current and former U.S. officials who spoke to the newspaper on condition of anonymity said that the United States was not authorized to share the information, which related to an ISIL threat involving the use of laptop computers on aircraft, with Russia.

BuzzFeed News and the New York Times corroborated the Post’s story shortly after it was published.

The President was reportedly eager to demonstrate to his hosts that he had access to the highest levels of classified information.

One official with knowledge of the meeting told the Post that Trump bragged, “I get great intel. I have people brief me on great intel every day.”

Trump already had stoked controversy by hosting Russian Foreign Minister Sergei Lavrov and Ambassador Sergey Kislyak at the White House last Wednesday, one day after abruptly firing FBI director James Comey. The President said that part of the reason he dismissed Comey, under whose watch federal investigators were probing whether Trump campaign staffers were colluding with Russian operatives who interfered in the U.S. presidential election, was his focus on this “Russia thing.”

A Russian media outlet snapped photographs of the three men laughing and chatting in the Oval Office, while American press were not allowed in the room.

The Post report alleged that Trump revealed information, including the city in ISIL-controlled territory where the U.S. intelligence partner said the threat originated, that hadn’t been shared with the United States’ “own allies.” He also reportedly told the visitors about the measures the U.S. has taken or is considering taking to counter the threat, according to the report, despite his frequent refusal to publicly telegraph his military strategy.

The Trump administration insisted Trump did not improperly share information about sources and methods in that meeting.

“The president and the foreign minister reviewed common threats from terrorist organizations to include threats to aviation,” National Security Adviser H.R. McMaster, who sat in on the meeting, told the Post. “At no time were any intelligence sources or methods discussed and no military operations were disclosed that were not already known publicly.”

The Post’s sources contradicted that account, saying senior White House officials needed to call the CIA and National Security Agency as soon as the conversation ended to try to prevent further information from leaking out.

Though the President has broad legal authority to disclose classified information, national security experts told the Post that Trump’s carelessness with these top-secret details compromises future intelligence-gathering efforts.

During the 2016 campaign, Trump heavily criticized his opponent, Hillary Clinton, for her use of a private email server as secretary of state, saying she compromised classified national security information.

Additional details on the ISIL plot were kept vague in the Post’s report because of their highly sensitive nature.

However, in March the Department of Homeland Security banned laptops and tablets from being carried onboard U.S.-bound flights from eight majority-Muslim countries. The U.S. is expected to expand that ban to include planes from the European Union, the Associated Press reported last week.

This post has been updated.