Earlier quoted context omitted.
They are not responsible for the actions of the military. Just because they are born in US doesn't make them responsible for the actions of the US military any more than someoe born in Canada, Brazil or Japan. People who have power over the actions taken are responsible, pretty much the person itself and also the higher chain of command for the said person who commits whatever act to be held responsible for.
The military gets orders from politicians who get elected by US citizens.
1. Those elected officials are not elected by everyone - in the case of GWB's first term (which many probably think of in this military context) it wasn't even a majority that elected him.
2. Those that do elect officials have a very small choice (lets say 2-3 people who could practically be elected). Further, I'd argue that most only vote on a few key issues, while the elected official has dominion over a vast number of issues.
I don't hold citizens as not at all responsible, but I think its at least fair to argue (in the above context) that the elected officials bear more responsibility - and blame - than the everyday citizen.