US military spending

The USA spends about as much on the military as the whole rest of the world combined!  This is clearly too much.  Does the US think that it is going to fight the whole world?  Does it think it could win such a fight?

Books versus journal articles

While working in fusion energy I collected far more journal articles than books.  While working in artificial intelligence I collected about the same number of journal articles but I bought (and read) far more AI books than fusion/plasma books.  Perhaps it is more difficult to get AI research published and this results in people assembling a larger number of book length collections of their work?