The majority of the Japanese people, while detesting Hussein, seem to consider the war devoid of a cause and not supported by the international community at large. The Japanese -- like many other nations -- judge Hussein as presently incapable of attacking America; therefore, U.S. action is unjustifiable.
To sum up: "There's a bad guy that kills his own people, but since the rest of the world sits on its hands, we should too"
So, what is a just war? When a majority of non-permanent members of the U.N. security council says it's okay to kill civilians? When there are no natural resources to bribe veto-bearing members of the council?
