Final answer:
The United States declared war on Japan the day after the attack on Pearl Harbor.
Step-by-step explanation:
After the attack on Pearl Harbor, the United States took the action of Congress declaring war on Japan the next day. This was a direct response to the surprise attack and marked the entry of the United States into World War II. The declaration of war signaled the commitment of the United States to actively engage in combat against Japan and its allies.
Learn more about United States response to Pearl Harbor attack