The top priority of Congress should be investigating President Donald Trump’s alleged leaking of classified information to Russian officials during a meeting last week, veteran journalist Dan Rather says.

“This is not politics. This is not policy,” the former CBS News anchor wrote on Facebook on Monday. “This is about the safety and security of the United States.”

Rather said there could be “no learning curve” for the president and his administration when it came to this kind of situation.

“If this reporting bears out, our security and that of our allies has been compromised,” he added, claiming it was “a gut check time” for “everyone who considers themselves to be a patriot.”