As a historian with a focus on the 20th century, I am well-versed in the events leading up to and during World War II. The question of who declared war first between Japan and the United States is a matter of historical record and interpretation.

On December 7, 1941, Japan launched a surprise military strike against the United States naval base at Pearl Harbor in Hawaii. This attack was a significant event that led to the United States' entry into World War II. The following day, December 8, 1941, the United States Congress declared war on Japan. This declaration was made in response to Japan's attack and was formalized through Public Law 77-328, which was signed into law by President Franklin D. Roosevelt. The declaration came an hour after President Roosevelt's "Infamy Speech," in which he addressed the Congress and the nation, describing the attack on Pearl Harbor as a "date which will live in infamy."

It is important to note that while the United States declared war on Japan, Japan did not formally declare war on the United States. Japan's attack on Pearl Harbor was considered an act of war, but there was no formal declaration from the Japanese government. This is a key distinction in the historical narrative, as it highlights the aggressive and unprovoked nature of Japan's actions.

The United States' declaration of war against Japan was a pivotal moment that set the stage for a broader conflict, which would eventually involve many nations around the world. The attack on Pearl Harbor and the subsequent declaration of war were catalysts that led to the United States becoming a major combatant in World War II.

In summary, the United States declared war on Japan first, in direct response to Japan's surprise attack on Pearl Harbor. This declaration was a critical step in the escalation of global conflict and marked the beginning of the United States' active involvement in World War II.

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On December 8, 1941, the United States Congress declared war (Public Law 77-328, 55 STAT 795) on the Empire of Japan in response to that country's surprise attack on Pearl Harbor the prior day. It was formulated an hour after the Infamy Speech of US President Franklin D. Roosevelt.read more >>