Japan's aggression was literally being fueled by the United States.
Beginning in late-1940, the United States grew less patient with Japanese atrocities and began to restrict trade with the Empire.

Japan signed a nonaggression pact with Stalin. This removed the threat of a Russian attack on Japan's new holdings.

By the end of 1940, the United States had ended shipments of scrap metal, steel, and iron ore to Japan. By midsummer, FDR made the fateful step of freezing all Japanese assets in the United States and ending shipments of oil to the island nation.Negotiations went nowhere. The United States was as unwilling to accept Japanese expansion and Japan was unwilling to end its conquests.

Un be known to the United States, a Japanese fleet of aircraft carriers stealthily steamed toward Hawaii.The goals for the Japanese attack were simple. Japan did not hope to conquer the United States or even to force the abandonment of Hawaii with the attack on Pearl Harbor. Almost 3,000 Americans were killed. Six battleships were destroyed or rendered unseaworthy, and most of the ground planes were ravaged as well.
When President Roosevelt addressed the Congress the next day and asked for a declaration of war, there was only one dissenting vote in either house of Congress.