So no troops in WW2, just leave Europe to the nazis?
It isn't uncommon for countries to come to the aid of others being invaded and USA has a long history of doing so, why do you think it should be reprehensible? Military and political alliances have advantages much bigger than what those who spew the myopic "not our problem" chant. Over 40 countries were in the coalition in Kuwait to repel Iraq, from Romania to Singapore to Egypt to New Zealand to Argentina, should the citizens of all those countries feel disgust that they were fighting someone else's war? Of course not.