United States IP address vs. email from Iraq?

I have been receiving emails from a Soldier that is supposed to be in Iraq. However, after reading some things typed I believe this person is a liar. I traced the IP address in one of his email headers and it came up being located in a US city. How can that be? If he is using a computer overseas, from his base, then why would the IP address show some city in the US? I can't tell you how pissed off I am to think that someone is pretending to be a United States Soldier and they may not really be one! Before I go off on this guy, I want to research what I think and get as many facts as I can about how the internet works over there and if his email address would reflect the IP address of the place it was maybe originally created or if it should reflect the actual location from where ever you send an email from? Thanks for the help