I have a different take....... recall that leftists are at root pacifists. That is they think Vietnam was the end of war. There can be no more war. It is settled history.
That is the Euro mindset. To be a warrior is to be a criminal if anyone other than another warrior is harmed. Since Hamas and all those that are users of terror tactics are not warriors, they can not be warred against.
Kerry doesn’t give a damn about dead Palestinian kids. His concern is that the IDF will be successful and a precedent will be set to condone war.
Leftists may use the language of pacifism, but what do you think the likes of Ayers, Dorhn and 0bama would do if given their druthers?