For progressive, educated people, Holocaust education was a double-edged sword. It made us keenly aware that the belief in the need for the existence of a Jewish state came from centuries of European Christian anti-Semitism culminating in the Holocaust. Therefore, when Israel justified its actions as defense against an existential threat, I think Europeans and American descendants of Europeans felt very nervous about rejecting that justification, since historically we're a big part of why they perceive an existential threat to their people.
I think we're well past that now, though.