Well he has talked repeatedly about taking Greenland "by force", which in itself wouldn't be a world war, but of course is still terrible.
I think the concern is that telling Ukraine to surrender their land after they were invaded by Russia will give Russia the confidence to start attacking other European countries. Traditionally, NATO would have protected us from that happening, but with Trump upsetting all our NATO partners, I'm kind of concerned that that won't help this time.
This, basically. He's said that we're going to take Greenland one way or another, is talking about taking the Panama Canal, is basically telling Russia we're on their side and Europe can deal with it themselves, and China is ramping up activities around taking Taiwan [1]. He's also classified the cartels as terrorist organizations and has talked about sending in elite US forces to take them out, which Mexico has said they would view as a violation of their sovereignty.
I've been listening to a lot of French news lately and France is already talking about needing to build more nuclear weapons and to extend nuclear protections across Europe, as the US has in a short few weeks completely alienated all of our allies from the past 80 years [2].
So, I don't know, seems like we're closer to everything going to shit globally than in any other time in my 40+ years.
Well, this is how yout tell anynone feeling like fixing like they might be in a position of fixing old grudges or grabbing some land - go for it! :P Not very safe and can get out of hand very very quickly...
I think the concern is that telling Ukraine to surrender their land after they were invaded by Russia will give Russia the confidence to start attacking other European countries. Traditionally, NATO would have protected us from that happening, but with Trump upsetting all our NATO partners, I'm kind of concerned that that won't help this time.