Basically, when one becomes part of the military, they are there to carry out policy, not make it.
One can argue the ideology all they like about whether or not it is defending our Freedom but one would be in the wrong place to be in the military and argue that point.
Now, one is free to vote for those they wish to see make policy that they can agree with, there is nothing wrong with that.
As far as the Middle East goes and "freedom", consider this set of lines from "Three Days of the Condor":
Higgins: It's simple economics. Today it's oil, right? In ten or fifteen years, food. Plutonium. Maybe even sooner. Now, what do you think the people are gonna want us to do then?
Joe Turner: Ask them?
Higgins: Not now - then! Ask 'em when they're running out. Ask 'em when there's no heat in their homes and they're cold. Ask 'em when their engines stop. Ask 'em when people who have never known hunger start going hungry. You wanna know something? They won't want us to ask 'em. They'll just want us to get it for 'em!
Freedom can mean The Bill of Rights, Freedom can mean not having to go hungry, Freedom can mean not having another country saying that you have to wait in long lines for a few gallons of gas, etc..