The second largest military (China) spend 6.7 times less than the United States. We spend $660+ billion, while China spends almost $99 billion. Canada and Germany only spend 1.3% of their GDP on military expense. The U.S. spends 4.3%. Only spending as much as these two other highly productive and advanced nations would equal a 70 percent reduction in our military spending. Our military budget would only be $198 billion. A savings of $462 billion.
But, for arguments sake, lets assume we could have an equally effective military spending just 4 times what China spends. We'd still be spending just under $400 billion. But we'd now have over $260 billion to spend on infrastructure, education, health care, Medicare, debt, etc.
A much better bang for the buck. (No pun intended.)