I admire Randy Barnett tremendously as a scholar. But I'm not finding any of his recent posts on Libertarians and War convincing. There's a lot there to respond to, but to take one example:

But would the U.S. Army been acting unjustly on Libertarian grounds it it goes to the aid of innocent civilians in Somalia, the Sudan, or Iraq? I do not see why. If these people are indeed the victim of horrible rights violations a solder regardless of whether his uniform is American or Iraqi would be justified in going to the defense of the victim according to Libertarian first principles.

This is an odd way to frame the question--as if the soldiers simply happen to be in Somalia or Iraq on vacation or something and happen to witness a rights violation. But how did American soldiers get there? They got there as part of military operations funded by resources forcibly extracted from the American taxpayer. Properly framed, the question, then, is something like:

Does it violate libertarian principle for the U.S. government to wrest scores of billions of dollars from the American taxpayer (possibly as much as $3,000 per American family in the case of Iraq,) in order to address rights violations committed half a world away against people not under its protection?

I'd say it does. I have a right to come to the defense of others. I do not have the right to steal Randy Barnett's car in order to do so.

Now, few outside of Spooner have written more convincingly than Professor Barnett about how hard it is to justify the state. So he might say the argument above applies just as well to taxation for the defense of Americans--it says the U.S. government can't come to the defense of Californians if it has to tax Kansans to do it. After all, none of us signed any kind of"social contract" or consented to a Constitution that pledges us to the" common defence" of Americans. But if even that limited justification of the state-as-common-defense-pact is problematic, how do you justify the state-as-world-liberator? Where does it get the authority to carry out these missions, however benevolent they might be?

In any event, I think it's odd to proceed as if the only rights in question are the rights of those who are to be liberated.