The concept of aggressive war may not be expressed with the precision of a scientific formula, or described like the objective data of the physical sciences. Aggressive War is not entirely a physical fact to be observed and defined like the operation of the laws of matter. It is rather an activity involving injustice between nations, rising to the level of criminality because of its disastrous effects upon the common good of international society. The injustice of a war of aggression is criminal of its extreme grosses, considered both from the point of view of the will of the aggressor to inflict injury and from the evil effects which ensue ... Unjust war are plainly crimes and not simply torts or breaches of contracts. The act comprises the willful, intentional, and unreasonable destruction of life, limb, and property, subject matter which has been regarded as criminal by the laws of all civilized peoples ... The Pearl Harbor attack breached the Kellogg–Briand Pact and the Hague Convention III. In addition, it violated Article 23 of the Annex to the Hague Convention IV, of October 1907 ... But the attack of Pearl Harbor did not alone result in murder and the slaughter of thousands of human beings. It did not eventuate only in the destruction of property. It was an outright act of undermining and destroying the hope of a world for peace. When a nation employs a deceit and treachery, using periods of negotiations and the negotiations themselves as a cloak to screen a perfidious attack, then there is a prime example of the crime of all crimes.  
On November 20, 1941, Nomura presented Proposal B, which offered to withdraw Japanese forces from southern Indochina if the United States agreed to end aid to the Nationalists Chinese, freeze military deployments in Southeast Asia (except for Japan's reinforcement of northern Indochina), provide Japan with "a required quantity of oil," and assist Japan in acquiring materials from the Dutch East Indies.  The United States was about to make a counteroffer to this plan, which included a monthly supply of fuel for civilian use. However, President Franklin D. Roosevelt received a leak of Japan's war plan and news that Japanese troopships were on their way to Indochina . He then decided that the Japanese were not being sincere in their negotiations and instructed Secretary Hull to drop the counterproposal.