I suppose it might be seen both ways. but the overall feeling I got from it wasn't “pro-war”, quite the opposite- I saw the hollowness of it all in the film. but then again, I guess it depends on your point of view when you see it.
I do have a feeling it changed when Clint got involved.. And now, that you got me thinking about it, that is probably when things moved from a straight-forward “American Hero- shooting up the bad guys” movie to what it became in the end…