It’s just not plausible to construe libertarianism as really being about massive, state-sponsored, centrally-planned, militarily-administered efforts to invade and reconstruct another country — let alone to imply that libertarians are by temperament the kind of people who are confident that enterprises like this usually succeed as planned.
... who if not libertarians can we depend on to remind us that the world isn’t fair, your plan brought misery instead, and that you’re just wasting your time — and probably making things worse — by initiating some Grand State Scheme to control unemployment, the market for rental accommodation, civilian air traffic or infant polio. This argument scales up to things like the forcible invasion, occupation and political reconstruction of faraway countries. Given that the country posed no credible threat to the U.S., Libertarians ought to have opposed the war and especially the subsequent occupation in Iraq.
Lots of people make this mistake (though I'm not sure that makes it any less stupid). No, the argument doesn't scale up, because the difference between national and international politics is more than just a difference in size: it's a totally different matter.
Politics, at it's most basic, is the system through which people negotiate and compromise with each other. Some political systems promote compromise more than others. Say what you like about Blair's Britain, but most of the laws on our books are somewhere inbetween the ideals of our various competing interests. Stalin's Russia, on the other hand, was a place of no compromise: you did what he told you, or you died.
Libertarianism applies to any situation in which people are capable of reaching agreements with each other else it is meaningless. The whole point of Libertarianism is that free people can make free agreements. People might refuse to compromise, but, as long as compromise is an option, they can live freely with one another.
The citizens of different democracies can negotiate and compromise with each other. It's often a long and convoluted process involving elected representatives, or unelected representatives chosen by elected representatives, and it doesn't leave everyone happy, but it broadly works. Free citizens of different nations can also, of course, negotiate and compromise with each other directly: I can make any sort of private arrangement I want with an American or a Czech. I can't with a resident of Iran, because all residents of Iran are directly controlled by the Iranian government and are not allowed to enter freely into agreements, especially with foreigners.
This is the reason why democracies so rarely go to war with democracies (the only modern example I'm aware of is the bombing of Serbia). They have other diplomatic mechanisms in place, and, crucially, those mechanisms work because there is a real and direct link of opinion between the nation's leaders and their people. When Bush negotiates with Chirac, it is true to say that, to some extent, the people of the USA are negotiating with the people of France. Not all of the people all of the time, obviously but there is enough representation to keep enough people happy that life can go on as normal. This is the great, and often overlooked, strength of democracy: that it doesn't merely help to sustain liberty, but that it makes people happy with their liberty. Happy enough not to go to war, at least.
Do I really need to go into any explanation of how Saddam didn't represent the Iraqi people? Of how the ideas of negotiation, compromise, and agreement between free people are nothing more than cruel jokes to the people of Iran or Saudi Arabia? Libertarianism simply doesn't apply here.
I hope that it soon will, though.