Folks, foreign aid is like 1% of the budget or something. It's not the reason military spending is so insanely high.
Incidentally, some scholars of Welfare policy have argued that the US' very high military spending is so high because the military-industrial complex basically works as a welfare program, providing jobs and various benefits that alleviate poverty in some area, and compensate for the lack of social spending. Of course, this kind of spending is far less effective than it would be if the money was directly focused on actual welfare spending, but it's certainly an interesting way to look at it.
It is certainly the government's most significant jobs program, and a significant contribution to the economy of many places in the US. That doesn't mean it's an efficient or sensible way to go about this, but it's hard for any social welfare program to replace that. Just providing benefits without the jobs and the sense of purpose (of being part of the nation's defense, or of an economy which supports it) doesn't do the same thing for people.
As far as jobs are concerned, the easy solution is to increase the civil service in areas that would be more socially useful (health care, education, the postal service, etc) and to increase spending on infrastructure building, which, from what I've heard, is badly needed in the US.
Regarding the "sense of purpose", this is of cousr beyond the scope of public policy, but I must say it is a sad reflection of the US policy that serving your country as a soldier is valued so much more highly than serving your country in countless other ways.
