The real reason why the U.S. so strongly supports Israel is the religious right which is the base of support for the Bush administration. They believe Israel is God's way of preparing for the Messiah's return and the current struggle is fulfilling the biblical prophecy for God to regather the Jews in Zion for that purpose as stated in Ezekiel 37:21:
"I will take the people of Israel from the nations among which they have gone, and will gather them from every quarter, and bring them to their own land."Basically this is a religious war and the notion that one side is right and just and the other wrong and evil doesn't make sense in that context.