H.R. McMaster, Trump’s national security adviser, held a briefing today, addressing reports that President Donald Trump shared highly classified information with top Russian officials.

WASHINGTON — President Donald Trump’s national security adviser says Trump didn’t know where information that he shared with Russian officials came from.

READ MORE: President Trump’s talk with Russian officials ‘wholly appropriate,’ McMaster says

The adviser, H.R. McMaster, says at a White House briefing that the information was available through “open-source reporting.”

McMaster says Trump hadn’t been briefed on the source or method of the information. McMaster didn’t deny that Trump had discussed information deemed classified.

Trump was later informed that he had broken protocol. White House officials then reached out to the National Security Agency and the CIA in an effort to contain any damage.

McMaster identified Trump’s homeland security adviser, Tom Bossert, as the official who contacted both agencies.

READ MORE: White House returns to crisis mode after Washington Post report

PBS NewsHour will update this story as it develops.