Dan Rather Slams President Trump for Claiming He'd Run into Florida School

Dan Rather's not buying President Trump rushing into the Florida high school to stop the mass shooter -- he says history shows that's just not his style.

We got the legendary CBS anchor in NYC Tuesday, and asked him to assess Trump's claim -- "I really believe I'd run in there, even if I didn't have a weapon." Rather started to say he wants to be respectful of the office of the Presidency ... then dropped a BIG ol' but.

He says Trump had a chance to stand up and show his bravery during the Vietnam War, but "ducked" it. Dan does acknowledge that was a long time ago, and the Prez could have changed.