I think an American president could force it but I can't imagine it being Trump, it would take real balls. The president would have to say to Ukraine "Look it sucks but you gotta give up the territory they occupy but in return you will be able to join NATO and the EU. If you say no we will withdraw all aid." To Russia the president would have to say, "OK, you get to keep the land you hold but Ukraine will join NATO and the EU, and sanctions will not be dropped. If you refuse the US will become more directly involved." No one would be happy but perhaps it could be done.