fighting for us?

I see alot of people say "thanks for fighting for us." 
I don't get it..the guys/gals in vietnam weren't "fighting
 for us" they were fighting for their lives..fighting to get 
home.That war wasn't OUR war.It was a asian civil war in which
 we had no buisness being involved in.I have brothers who were there.
 (101st airborne).They will echo my opinions.I don't believe 
thanks are in order for "fighting for us" but rather for the
 fact that they went in many of our steads.For that i am truly
 thankful..yet ashamed of our govt. for putting those guys in
 that suituation.sorry if i offended anyone but that's my opin
ion.