Yeah, it's good to mention. Still I believe that from the outside, in practice it doesn't matter much: if Trump gives the order to invade an ex-ally, who is to

Yeah, it's good to mention. Still I believe that from the outside, in practice it doesn't matter much: if Trump gives the order to invade an ex-ally, who is to know if the US would do it or not? To the outside it is a risk, and a country making that kind of threats probably does not count as an "ally".