Sometimes it is about money. A quick Google search for your answer produced many responses but I found this one in particular to be relevant to your question:
Joseph Sisco, a former Assistant Secretary of State for Near Eastern and South Asian affairs: "I want to assure you… that if we were not getting full value for our money, you would not get a cent from us." In fact, Israel has long been America 's biggest strategic bargain.
Let's examine some facts. For FY2009, U.S. military grants to Israel was $2.55 billion = $2.55BViewed over the five year period of 2005–2009—total U.S. military aid was approximately $12B.What has the U.S. received from Israel in return?
Israel must spend about 74 percent of U.S. military aid in the United States, where it provides jobs for an estimated fifty thousand American workers.
Unknown to many observers, U.S. military aid to Israel creates a demand for, and the purchase of, tens of billions of dollars worth of U.S. weaponry by Saudi Arabia and other Arab states. U.S. grants to Israel —far from imposing a burden on the American tax payer—actually enriches the American economy.
Gen. George Keegan, a former chief of U.S. Air Force Intelligence, between 1974 and 1990 said Israeli aid to America was worth between $50–80B in intelligence, research, development savings, and Soviet weapons systems captured and transferred to the Pentagon, and testing Soviet military doctrines up to 1990 when the USSR collapsed.
Total exports from the U.S. to Israel between 2005 and 2009 amounted to $57.6B—almost five times the $12B Israel received in U.S. aid during this period. The annual average of U.S. exports to Israel during this period was $11.7B, more than five times the average American aid package!
Israel constantly relays to the United States lessons of battle and counter-terrorism, which reduce American losses in Iraq and Afghanistan, prevent attacks on U.S. soil, upgrade American weapons, and contribute to the U.S. economy. Innovative Israeli technologies boost U.S. industries.The vice-president of the company that produces the F-16 fighter jets told Ettinger that Israel is responsible for six hundred improvements in the plane's systems, modifications estimated to be worth billions of dollars, which spared dozens of research and development years.
Without Israel , the United States would have to deploy tens of thousands of American troops in the eastern Mediterranean Basin , at a cost of billions of dollars a year.In 1981, Israel bombed the Iraqi nuclear reactor, thus providing the United States with the option of engaging in conventional wars with Iraq in 1991 and 2003, thereby preventing a possible nuclear war and its horrendous consequences.In 2005, Israel provided America with the world's most extensive experience in homeland defense and warfare against suicide bombers.
answers.yahoo.com...
edit on 11/20/2012 by manta78 because: (no reason
given)

