Why do I oppose war? I oppose war because I oppose the initiation of force in any fashion. I support the non-aggression principle (NAP) which asserts that all individuals possess the unalienable natural rights of life, liberty, and property; and that no one may ever justly initiate force against these rights. (The NAP does not in any way prohibit self-defense.) War directly targets and indirectly harms individuals who are not guilty of initiating force, and thus, I cannot support the waging of war for any reason or in any context.
I denounce all varieties of government "wars" including the "war on poverty," the "war on drugs," and the "war on terror." All of these grand facades have been nothing but excuses to seize and redistribute property; to strip individuals of their civil liberties and natural rights; and to kidnap, cage, enslave, and murder both random civilians and political and philosophical opponents of those in power. Author Randolph Bourne once said that "war is the health of the state," and that statement holds true whether the war is a "conventional war" in which all individuals within a geographical region are targeted or a perverse reinvention of the notion concocted in an attempt to justify battlefield-style atrocities in domestic policy.
For more reading on the subject of war and the non-aggression principle, I would suggest "War, Peace, and the State" by the great Murray Rothbard as well as "Libertarian Warmongers," "Bloodthirsty 'Libertarians'," and "Randy Barnett: Pro War Libertarian?" by the fabulously insightful Dr. Walter Block (Professor of Economics at Loyola University New Orleans and Senior Fellow with the Ludwig von Mises Institute.)