Was the Attack on Pearl Harbor Illegal?

Was the attack on Pearl Harbor illegal? This question has lingered in historical discourse, sparking debates about international law, wartime ethics, and Japan’s role in one of the most infamous events of World War II. On December 7, 1941, the Imperial Japanese Navy launched a surprise strike on the U.S. naval base at Pearl Harbor, killing 2,403 Americans and plunging the United States into World War II. But was this act of war legally justified under the international agreements of the time? Let’s delve into the evidence.

At the heart of the question lies the 1907 Hague Convention III – The Opening of Hostilities, which set out specific protocols for declaring war. Article 1 of this convention explicitly states that no attack should be initiated without prior and explicit warning. Japan did compose a message intended to warn the United States, but it was not delivered until after the attack had already begun.

Additionally, Article 2 of the same convention stipulates that neutral powers must be notified of a state of war before hostilities commence. This regulation was clearly disregarded during the Pearl Harbor attack, as Japan and the United States were still engaged in peace negotiations at the time. This lack of proper warning violated the very essence of these international agreements.

Another pivotal document influencing the legality of Pearl Harbor is the Kellogg-Briand Pact of 1928, signed by both Japan and the United States. This treaty renounced war as a means of resolving international disputes. Japan’s decision to launch a surprise military strike, ostensibly in response to U.S.-imposed trade embargoes, contravened this pact. While Japan may have perceived these embargoes as acts of aggression, the pact explicitly forbade using war as a resolution to such conflicts.

Admiral Isoroku Yamamoto, the architect of the Pearl Harbor attack, reportedly acknowledged the potential repercussions. He is said to have recognized that, should Japan lose the war, the attack on Pearl Harbor would be classified as a war crime—a forewarning of the eventual judgment passed by the Tokyo War Crimes Trials.

Following Japan’s defeat in 1945, international legal proceedings sought accountability for wartime atrocities, including the attack on Pearl Harbor. The Tokyo War Crimes Trials scrutinized Japan’s actions, charging several high-ranking officials with crimes against peace and murder. Among them were Prime Minister Hideki Tojo, Foreign Minister Shigenori Togo, Minister of the Navy Shigetaro Shimada, and Chief of Naval General Staff Osami Nagano.

The tribunal concluded that the attack on Pearl Harbor was unequivocally illegal under international law. It violated both the 1907 Hague Convention and the Kellogg-Briand Pact, cementing its place as a breach of wartime ethics and global agreements.

While the legal determination is clear, the attack on Pearl Harbor remains a complex event. It marked a turning point in global history, ushering the United States into World War II and redefining the balance of power in the Pacific. Yet, its legacy is inextricably tied to its violation of international norms.

The question of its legality serves as a reminder of the importance of adherence to global treaties, even during times of conflict. Pearl Harbor stands as a cautionary tale about the consequences of disregarding international agreements and the enduring impact of such actions on global history.