Israel is simply not a good ally. Not sure why anyone would disagree, but just in case, here's an essay written a couple years ago, preceding a book released by the same authors.
Israel is the only recipient of foreign aid by the US to not have to account for how the money is spent. Billions per year, about $500 per Israeli, goes to Israel in the form of cash, military weaponry, and military intelligence. Why? Because of how powerful the domestic lobbies are which have no purpose other than to further the goals of Israel.
Still wondering why we got attacked on 9/11/2001? You shouldn't be.