Elvin - The US spends money on the military for many different reasons. One of the main ones is that they subsidize the private industry by their military spending. When the US government pays Boeing to develop jet fighters -that technology goes into the private development of commercial airliners. That is why Bombardier in Canada needs subsidies -the US subsidizes industry with their military spending. Computers and the internet were not developed by Bill Gates or Stephen Jobs -they just used military  technology in the private sector.
A great deal of US military spending could be renamed 'subsidies'.