On December 7, 1941, nearly 90 years of American-Japanese diplomatic relations spiraled into World War II in the Pacific. Learn how.

As a result, Japan launched a surprise attack on Pearl Harbor, aiming to neutralize the U.S. Pacific Fleet and secure its dominance in Asia. This act precipitated the United States’ entry into World War II, marking a dramatic shift from tense peace to outright conflict.

Japan's Axis allies, including Nazi Germany, declared war on the United States days after the attack, bringing the United States into World War II. The Pacific War was marked by atrocities towards both civilians and combatants alike, such as Japanese conduct towards both civilians and allied prisoners of war and allied desecration of Japanese dead.

Japanese-American Relations at the Turn of the Century, 1900–1922. In the first two decades of the twentieth century, the relationship between the United States and Japan was marked by increasing tension and corresponding attempts to use diplomacy to reduce the threat of conflict.

Between 1937 and 1941, escalating conflict between China and Japan influenced U.S. relations with both nations, and ultimately contributed to pushing the United States toward full-scale war with Japan and Germany.