that's a very good point, but there hasn't been an official Declaration of War since 1942 per the wiki (which is a whole nother issue, albeit a very valid one).

https://en.wikipedia.org/wiki/Declaration_of_war_by_the_Unit...

Rachel Maddown recently came out with a book on this, called "Drift: The Unmooring of American Military Power."

http://www.nytimes.com/2012/04/15/books/review/drift-by-rach...