Updated at 7:17 p.m. ET

President Trump revealed “highly classified information” to two top Russian officials during a controversial Oval Office meeting last week, according to a report from The Washington Post.

The Post, citing current and former U.S. officials, reported Monday evening that the information relayed by the president to Russian Foreign Minister Sergey Lavrov and Ambassador Sergey Kislyak “jeopardized a critical source of intelligence” on ISIS:

“The partner had not given the United States permission to share the material with Russia, and officials said Trump’s decision to do so endangers cooperation from an ally that has access to the inner workings of the Islamic State. After Trump’s meeting, senior White House officials took steps to contain the damage, placing calls to the CIA and the National Security Agency.

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” ‘This is code-word information,’ ” said a U.S. official familiar with the matter, using terminology that refers to one of the highest classification levels used by American spy agencies. Trump ‘revealed more information to the Russian ambassador than we have shared with our own allies.’ ”

Trump also reportedly boasted to the Russians about the intelligence he was receiving, telling the two men, “I get great intel. I have people brief me on great intel every day”:

“Trump went on to discuss aspects of the threat that the United States learned only through the espionage capabilities of a key partner. He did not reveal the specific intelligence-gathering method, but he described how the Islamic State was pursuing elements of a specific plot and how much harm such an attack could cause under varying circumstances. Most alarmingly, officials said, Trump revealed the city in the Islamic State’s territory where the U.S. intelligence partner detected the threat.

“The Washington Post is withholding most plot details, including the name of the city, at the urging of officials who warned that revealing them would jeopardize important intelligence capabilities.”

BuzzFeed also confirmed The Post‘s report, with one U.S. official saying that the disclosures from the president to the Russians were “far worse than what has already been reported.”

The New York Times also noted that “Trump’s disclosure does not appear to have been illegal — the president has the power to declassify almost anything. But sharing the information without the express permission of the ally who provided it represented a major breach of espionage etiquette and could jeopardize a crucial intelligence-sharing relationship.”

Trump’s meeting with the Russians came last Wednesday, the day after he fired FBI Director Jim Comey, who was overseeing an investigation into Russian meddling in the U.S. elections and possible ties between the Trump campaign and Russia.

The visit was fraught with bad optics, and Kislyak’s attendance — only confirmed by photos from Russian state media — was especially notable because he has been at the center of many of the Trump administration’s controversies involving Russia. No U.S. media was allowed in to photograph the meeting, only TASS, Russia’s official news agency.

Trump’s first national security adviser, Michael Flynn, was forced to resign just over three weeks into the job after it was revealed he had discussed Russian sanctions with Kislyak and then subsequently misled Vice President Pence about those conversations. And Attorney General Jeff Sessions was forced to recuse himself from any involvement in the FBI’s investigations into Russia after it was revealed that he twice met with Kislyak despite testifying he had had no contact with Russian officials during his confirmation hearing.

National security adviser H.R. McMaster told reporters outside the White House that the “story that came out tonight as reported is false.”

“At no time were intelligence sources or methods discussed, and the president did not disclose any military operation that were not already publicly known, McMaster said. However, The Post story and other subsequent reports didn’t say that it was sources, methods or military operations discussed, but simply classified information.

“I was in the room, and it didn’t happen,” McMaster said at the end of his abrupt statement. He departed without taking questions.

“During President Trump’s meeting with Foreign Minister Lavrov, a broad range of subjects were discussed among which were common efforts and threats regarding counter-terrorism,” Secretary of State Rex Tillerson said in a statement. “During that exchange the nature of specific threats were discussed, but they did not discuss sources, methods or military operations.”

Senate Intelligence Committee Vice Chairman Mark Warner, D-Va., said that if The Post‘s report was true, it was “inexcusable.”

Eliot Cohen, a former counselor to Secretary of State Condoleezza Rice under President George W. Bush, said on Twitter that if Trump had given the classified material to the Russians deliberately, “it would be treason.”

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