Opposition to unjust warfare is one of the basic concepts in the Mohist School of thought. It regards immoral and aggressive wars as acutely harmful to society. Not only does the country being attacked suffer great damage, the people of the country that starts the war also suffer serious casualties and property losses. Therefore, Mohists held that unjust wars should be prohibited. They took specific measures to prevent aggressive wars between nations, and conducted research into defensive tactics and armaments.

If one wishes to be humane and just and become a gentleman with high moral standards, he must both observe the way of the sage kings, and advance the interests of the state and the people. In order to achieve these goals, the principle of prohibiting unjust wars cannot be disregarded. (Mozi)