Diplomatically, the United States condemned Japanese aggression and called for a peaceful resolution to the conflicts in Asia. The United States also imposed economic sanctions on Japan, including an embargo on the sale of oil and steel.
Economically, the United States provided economic aid to China and other countries that were fighting Japan. The United States also increased its own military spending in order to deter Japanese aggression.
Militarily, the United States sent military advisers to China and other countries that were fighting Japan. The United States also provided military equipment to these countries. In 1941, the United States and Japan went to war after the Japanese attacked the American naval base at Pearl Harbor.