If it weren't for the fact that most Libertarians wouldn't condone fighting a pre-emptive war unless our enemy was "huddled on our own borders ready to attack," I'd vote for them as well. But alas, Libertarians seem completely unable to grasp the concept that ICBMs and WMD have rendered their 18th century military defense model obsolete.
Somehow "Letters of Marque" don't seem so appropriate in this day and age.