This is a must read:

Israel: Strategic Asset or Liability?

"Is Israel a strategic asset or liability for the United States? Interesting question. In my view, there are many reasons for Americans to wish the Jewish state well. Under current circumstances, strategic advantage for the United States is not one of them. If we were to reverse the question, however, and to ask whether the United States is a strategic asset or liability for Israel, there would be no doubt about the answer.

"American taxpayers fund between 20 and 25 percent of Israel’s defense budget (depending on how you calculate this). Twenty-six percent of the $3 billion in military aid we grant to the Jewish state each year is spent in Israel on Israeli defense products. Uniquely, Israeli companies are treated like American companies for purposes of U.S. defense procurement. Thanks to congressional earmarks, we also often pay half the costs of special Israeli research and development projects, even when — as in the case of defense against very short-range unguided missiles — the technology being developed is essentially irrelevant to our own military requirements. In short, in many ways, American taxpayers fund jobs in Israel’s military industries that could have gone to our own workers and companies. Meanwhile, Israel gets pretty much whatever it wants in terms of our top-of-the-line weapons systems, and we pick up the tab."