Don Boudreaux of Cafe Hayek wrote a great argument for libertarian opposition to the Iraq war called An Open Letter to My Libertarian Friends Who Don't Understand My Opposition to the War in Iraq:
Read this articleRemoving a dictator is child's play for a military as awesome as that of the United States. So Hussein is now history. But because the underlying causes that put him in power to begin with are still in place in Iraq, that country likely will soon revert to another dictator -- one different in name and different in style, but a brute nevertheless. He will oppress, kill, and impoverish. (The notion that a poweful military can uproot dysfunctional cultural, political, and economic root causes of tyranny strikes me as naive in the extreme. Just as your local policeman can protect Ms. Jones from her husband's physical abuse but can't hope to counsel their marriage into a happy one, so, too can a military remove a tyrannt like Hussein but can't hope to cure that society of what really ails it.)
And Americans will be blamed for this tragedy. The fact that our President meant well will matter little to people tyrannized by the government that replaced the one we abolished. Americans will be hated more intensely, and suffer greater danger of terrorist attacks.