I've answered that question about my support by arguing in summary that 1) libertarianism is not necessarily isolationist, 2) that anyone has the right to liberate a slave state, though not a duty to do so, and that 3) in the context of Arab terrorism Saddam Hussein, his subterfuge over weapon inspections, terrorist activity, and his military-industrial infrastructure taken together constituted an objective threat.
But that still doen't answer the question itself. On the first of those issues, Democide researcher , Nobel Prize nominee and former libertarian R.J. Rummell suggests that libertarians have become isolationists, and his argument illuminates and helps answer the question posed above.
Rummel now calls himself a 'freedomist' (unneecessarily in my view), and he recently issued a challenge at his Freedomist Network blog to any anti-war libertarian "who wishes to make a reasoned argument for isolationism, or from a libertarian perspective, an argument against our war in Iraq. I will respond in a page, and then the libertarian will have a page to rebut me."
The challenge is here. The response to this, from Tom Knapp is here, followed by Rummel's response and Knapp's rebuttal. And just so you know Knapp's credentials, Robert Bidinotto raises them here and here.
So why has Rummel abandoned the name 'libertarian'?
[L]ibertarian is what I called myself until recently. I remain libertarian in domestic policy, which is to say the more domestic freedom from regulation, government control, taxation, and oppressive laws, the better up to a point. I am not an anarchist, but believe social justice means minimal government consistent with protecting and guaranteeing all have equal civil and political rights.Now, I agree entirely with him that "by their isolationism, [some] libertarians are making the world safe for the gangs of thugs (called dictatorships) that murder, torture, and oppress a people, and rule by fear." I agree that this issue has divided libertarians, but this libertarian doesn't see the need to change my 'name' -- the inconsistent isolationists can do that.
However, on foreign policy the libertarian, with some exceptions, is an isolationist, fundamentally opposed to foreign involvements and interventions. Let international relations also be free, the libertarians say, which means free trade and commerce, and freedom for other countries to do whatever they want with their people. Not our business.
On this, the libertarians are blinded by their desire for freedom, not realizing that everything, including freedom demands contextual qualification (should those with a dangerous infectious disease remain free, when they could spread it far and wide, killing maybe hundreds with it?). By their isolationism, libertarians are making the world safe for the gangs of thugs (called dictatorships) that murder, torture, and oppress a people, and rule by fear.