I suggest that it would be convenient to the United States interests if Israel were to prosper in peace. I am not sure is in America's interest to make war on behalf of Israel or to try to arrange all of the chess pieces in the Middle East to make that world safe for Israel.
Moreover, support for Israel carries a price and we ought to consider whether that price is worth paying for what we get. In sum, we support a 8 million Israelis against hundreds of millions of Arabs and more than 1 billion Muslims with a ton of oil. If what we get for that support is domestic support for politicians at the polls, I oppose it. If what we get out of that support is a safer world for the United States, I favor it.
This is a standard which I do not apply only to Israel, but to all our so-called "allies." If you look at my post #37, I think you will see I raise much the same questions and that applies to your question about whether Arab communists are different. If a radical leftist Obama is in bed with radical Islam that is not a paleo-conservative alliance rather it's one which ultimately must come to a death struggle between communism and Islam.
More important than our relationship with Israel is our strategy concerning Islam. We have tried invading and occupying nations, and that has failed. We have tried leading from behind, and that has failed. We have tried supporting the Muslim brotherhood, and that has failed.
Edison could try hundreds of ways to make a lightbulb and fail but we might not have the space or time for so many failures.
During the Cold War, a lot of the Islamic world sided with the US against the Soviets (Afghanistan, Saudi Arabia, etc) because Communism was (obviously) incompatible with their theocratic Islamism.
With this in mind, I never understood how Islamists and left-wing atheists could put their differences aside so easily in today's political world. You'd think that Islamists would object of the "blasphemy" of the Left, while Leftists would detest Islam for the very things that they hate Christians for. Yet Leftists seem to be bothered a lot more by Christian bakers in America not selling gay wedding cakes to homosexuals or by some preacher saying that a woman's place is the house and home than they are by Saudis beheading homosexuals or stoning women to death for pre-marital sex.