The principal national security and economic policy interest of the United States in the Middle East is to keep the oil states happy and the oil flowing cheaply. Israel is a substantial hindrance to that interest. American support for Israel has other roots--domestic political roots, guilt-over-not-entering-WWII-earlier roots, and a (miscalculation) that an Isreael confident of American support will be much more willing to deal.
But to say that Israel is an "outpost" of the American "empire" is totally dorky--reveals a systematic failure to think. Since George C. Marshall was Secretary of State, American diplomats have, way down in their deepest hearts, thought just how much easier the projection of American power and influence into the Middle East would have been if Israel had never been established. Israel is a source of weakness in America's "empire": it is not a functional part of it...
Brad DeLong