The Theory of U.S. Foreign Policy -- I http://mrzine.monthlyreview.org/2010/hs120710.html

The United States today, by comparison, is a much simpler case. It is completely dominated by monopoly capitalism, remnants of earlier social forms (particularly the independent farming class) being largely powerless.  

A large and growing warfare program, on the other hand, not only "solves" the economic problem of monopoly capitalism but also helps to preserve intact the existing class structure with its graded system of rank, status, and privilege. Furthermore, and this is of the greatest importance, the military might which it creates is absolutely essential to the maintenance of the world-wide economic empire which provides monopoly capitalism with indispensable (and highly profitable) raw materials, markets, and investment outlet