USA: Why we fight (2005)

The grim warning by Dwight D. Eisenhower on his farewell address sounds today like the prophecies of Cassandra. This documentary features interviews with many prominent individuals, including Senator John McCain, retired CIA experts, pentagon experts as well as ordinary citizens. The premise is, as the title suggests, to explore the reasons that have led the US to wage wars, although the main part of the movie concentrates on the decision to invade Iraq.
Trailer:

Full movie:

Things have certainly changed since 2005, with the Obama administration coming to power in 2008, but it's still worth a watch.

References:
Hiroshima. Was it necessary?
The Project for a New American Century
Iraq body count