President Trump revealed highly classified information to the Russian foreign minister and ambassador in a White House meeting last week, according to current and former U.S. officials, who said Trump’s disclosures jeopardized a critical source of intelligence on the Islamic State.

The information the president relayed had been provided by a U.S. partner through an intelligence-sharing arrangement considered so sensitive that details have been withheld from allies and tightly restricted even within the U.S. government, officials said.

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. …

As president, Trump has broad authority to declassify government secrets, making it unlikely that his disclosures broke the law. ….

In his meeting with Lavrov, Trump seemed to be boasting about his inside knowledge of the looming threat. “I get great intel. I have people brief me on great intel every day,” the president said, according to an official with knowledge of the exchange.

Trump went on to discuss aspects of the threat that the United States learned only through the espionage capabilities of a key partner. ….

U.S. officials said that the National Security Council continues to prepare multi-page briefings for Trump to guide him through conversations with foreign leaders, but that he has insisted that the guidance be distilled to a single page of bullet points — and often ignores those.

“He seems to get in the room or on the phone and just goes with it, and that has big downsides,” the second former official said. “Does he understand what’s classified and what’s not? That’s what worries me.”

Trump revealed highly classified information to Russian foreign minister and ambassador