Well for one, his public and sharp criticism of NATO countries that he's decided are not or have not been spending enough on defense. Airing that stuff out in the open sows division and weakens the unity of the alliance. And it often seems like he is angling toward pulling the US out entirely at some point--though I'm not sure he'd be able to.

Why would NATO members not spend enough on defence? NATO members would never spend less on defence than they should, that is clearly an insane and slanderous lie that only a pro-Putin idiot liar would ever make. Trump is probably trying to goad them into tanking their economies by redirecting too much spending to defence so that Russia can be victorious over them in the global economy. Thanks for explaining. It's not quite what I would describe as openly pro putin but I understand the need for some level of dishonesty when faced with some so blatantly openly pro putin.