What Trump is demanding here is that when the US engages in an unnecessary and unprovoked war of aggression and conquest, other countries are obligated to join

What Trump is demanding here is that when the US engages in an unnecessary and unprovoked war of aggression and conquest, other countries are obligated to join in. To agree to that would not only be deeply immoral, but is effectively saying that the US gets to decide what is done with their military power.