If proven true, that disclosure would mean Trump violated a key diplomatic principle for which he repeatedly hammered Democratic rival Hillary Clinton during the 2016 campaign.
National security adviser H.R. McMaster said in a statement provided by White House press secretary Sean Spicer following the disclosure that Trump and the officials, Russian Foreign Minister Sergey Lavrov and Russian Ambassador to the US Sergey Kislyak, discussed "common threats."
"The President and the foreign minister reviewed common threats from terrorist organizations to include threats to aviation. At no time were any intelligence sources or methods discussed and no military operations were disclosed that were not already known publicly," McMaster's statement read.
CNN has not independently verified The Washington Post's report that Trump relayed code-word information jeopardizing a critical source of intelligence on ISIS, but Trump's criticism of Clinton's handling of classified information during the campaign are well documented and add a sense of irony to Monday's reporting.
House Speaker Paul Ryan also criticized Clinton over her email practices and said last summer that "individuals who are 'extremely careless' with classified information should be denied further access to such info."
Here are some of Trump's past public statements about the handling of classified information, specifically referencing the investigation into Clinton's use of a private email server while secretary of state.
July 5, 2016: During a rally in Raleigh, North Carolina, Trump said, "(Clinton) sent vast amounts of classified information, including information classified as top secret. Top secret. OK? And this is where they said that she was extremely careless and, frankly, I say grossly incompetent. She would be such a lousy president, folks. So sad. OK, the lives of American people were put at risk by Hillary Clinton."
July 6, 2016: Then-candidate Trump tweeted, "Crooked Hillary Clinton and her team 'were extremely careless in their handling of very sensitive, highly classified information.' Not fit!"
In that tweet, he was quoting James Comey, who was the FBI director until Trump fired him last week.
July 11, 2016: During a speech in Virginia Beach, Virginia, Trump told a crowd that Clinton would not be able to pass a background check. "This was not just extremely careless with classified material, which is still totally disqualifying. This is calculated, deliberate, premeditated misconduct," he said.
"If elected, Hillary Clinton would become the first president of the United States who wouldn't be able to pass a background check," Trump added.
August 16, 2016: Speaking in West Bend, Indiana, Trump said, "In my administration, I'm going to enforce all laws concerning the protection of classified information."
September 4, 2016: Trump tweeted: "Lyin' Hillary Clinton told the FBI that she did not know the 'C' markings on documents stood for CLASSIFIED. How can this be happening?"
September 6, 2016:
According to a transcript of a Greenville, North Carolina, speech on the American Presidency Project
, Trump said, "Like the Cold War, we also need to fight this battle by collecting intelligence and then protecting our classified secrets."
Talking about Clinton at the same event, Trump said, "We can't have someone in the Oval Office who doesn't understand the meaning of the word confidential or classified."
September 9, 2016: In a speech, Trump said, "(Clinton) couldn't even remember whether she was trained or handling classified information -- didn't remember anything about it."
September 13, 2016: During a speech in Clive, Iowa, Trump said Hillary Clinton "put classified information in the reach of our enemies."
November 3, 2016: In Jacksonville, Florida, Trump said, "It is believed that no less than five foreign intelligence agencies successfully hacked in to Clinton's illegal, unsecure server, which contained classified information, creating an ongoing security threat to the United States."
February 16, 2017:
At a White House press conference, Trump spoke about leaks
of his conversation with Mexican President Enrique Peña Nieto. Trump said, "It was a very confidential, classified call. But I called Mexico. And in calling Mexico, I figured, oh, well that's -- I spoke to the president of Mexico; I had a very good call. All of a sudden, it's out there for the world to see. It's supposed to be secret. It's supposed to be either confidential or classified, in that case."
March 22, 2017:
In an interview with Time magazine
, Trump addressed leaks in the early days of his presidency, saying: "Classified. That's classified. You go to prison when you release stuff like that. And who would release that?"