- Declaration of war: On December 8, 1941, the United States declared war on Japan. This declaration was followed by declarations of war from other Allied countries, including the United Kingdom, Canada, and Australia.
- Mobilization of industry: The United States quickly mobilized its industry to produce war materials. This included the construction of new factories, the conversion of existing factories to war production, and the training of workers.
- Creation of the Manhattan Project: The United States began the Manhattan Project, a top-secret research program to develop an atomic bomb. The project was successful in developing and detonating two atomic bombs, which were used to attack the Japanese cities of Hiroshima and Nagasaki in August 1945.
- Military operations: The United States launched a series of military operations against Japan, including the Doolittle Raid, the Battle of Midway, and the Battle of Iwo Jima. These operations were successful in destroying Japanese ships and aircraft, and in capturing important islands that were used as staging grounds for attacks on Japan.
- Economic sanctions: The United States imposed economic sanctions on Japan, which cut off the country's access to essential resources. These sanctions contributed to the weakening of the Japanese economy and the eventual defeat of Japan.
- Diplomatic efforts: The United States engaged in diplomatic efforts to build support for its war against Japan. This included the Cairo Declaration, which was issued by the United States, the United Kingdom, and China in December 1943, and which set forth the Allies' goals for a post-war world.