As president, when does Trump cross the line when he specificall

Avalon - As president, when does Trump cross the line when he specifically names news outlets by tweeting "the fake news media (New York Times, NBC, ABC, CBS, CNN) is not my enemy, it is the enemy of the American people." Can Trump be sued by these networks for defamation, slander, etc.? I have never seen a president use his office in this manner to intentionally undermine the fundamentals of the First Amendment. It seems like lawyers and courts will be the only thing from stopping Trump from spewing this outrageous claim.