So, does one owe alegience to a country because of an accident of birth? Does one have freedom of conscience, or can the ruling powers determine what's legal or illegal for you to believe?
In a conflict both parties are answering their country's call. Both sides are patriotic and abdicating their moral responsibility to whatever group is currently holding the reins of power.
Are both sides in the right? Are good guys fighting good guys? Does loyalty to country trump one's individual responsibility for his own actions?
How is it right for one to cede moral responsibility to another and commit acts he'd normally consider immoral on another's instructions?
Questions like this are easier to explore now that there's no conscription, although one can define "support" or "allegiance" in any number of ways.
I knew someone who believed that anyone who pays taxes to the US government is responsible for what the government does with the money. If tax money is used to go to war, then every taxpayer is seen as just as morally responsible as those who pull the trigger. I'm not sure I strictly agree with that, although I can understand the argument.
Even those who reap the benefits and advantages of living in a first-world economy could be seen as indirectly gaining from war and US militaristic hegemony around the world.
I don't have any illusions that it's all about "freedom" or "making the world safe for democracy." Some apologists might argue that we really don't have any choice - that we're stuck in a world system not of our own creation, but have to deal with it just the same.
"Patriotism" is kind of a double-edged sword. I think one can be a patriot and support defending American territory, if and when it is ever directly attacked by a foreign military force. Likewise, if any close, long-term allies are directly attacked by a foreign military force. But it's different with some of the interventionist wars and other "police actions" we get ourselves involved in. We get involved in other countries' civil wars and internal politics, which some might see as going too far.