It’s not hard to explain. Maybe someone should do that.
I think he sincerely believes this because he literally knows nothing about American history and seems to be very impressed with something he heard or watched recently that’s given him some very warped ideas about World War II. Maybe Melania should put on a History Channel documentary about the Cold War. He seems not to have heard of it.
I wouldn’t think this was hugely relevant — we know he’s stupid — except that he’s justifying completely re-ordering U.S alliances and the world economy by not only creating an alternate reality in the present, he’s now rewriting the past.
This is what happens when a narcissistic megalomaniac realizes that nothing and no one can ever hold him accountable for anything. He’s creating the world anew.