there is a deeper american view on this. american hegemony is necessary to continue to exchange worthless money printer fiat for goods and services. probably the greatest deal any nation has had since the days of the british empire and to go further back you're looking at the romans. trump obviously wants to stop exchanging worthless paper for goods and services and instead intends americans have to work much harder and create value to genuinely earn any kind of exchange in future. this is baffling, unemployment in shithole states is a price worth paying for literally trillions of dollars of effectively free stuff but populism tends to back people into silly corners. the british empire did eventually find the costs of pax britannia were greater than the gain but the us has at least another century until that kicks in, why they are leaping early isn't clear. make the transition to chinese rule cleaner maybe? so if you've genuinely given up your advantages, you don't need to hegemony and ukraine is the most visible element, although its really giving up on israel that would be the issue (perhaps he does this once his feet are under the table). it all seems like absolute madness which is why its hard to explain even on its own terms.
United Kingdom