Pearl Harbor was attacked to prevent the invasion of the “Southern resource area”
Tensions between Japan and the United States had been rising for more than a decade when the first Japanese bomber flew over Pearl Harbor on December 7, 1941, making war seem unavoidable. The primary cause of the attack on Pearl Harbor was the headquarters of the U.S. Pacific Fleet.
Without the United States' supply of natural and industrial resources, particularly oil, Japan's military services would be seriously impacted. The United States started implementing economic sanctions against Japan, including trade embargoes on the export of aircraft, oil, and scrap metal among other crucial commodities and provided financial support to the Guomindang forces when Japan conquered French Indochina in 1940. When Japan approved the Tripartite Pact with Germany and Italy, more embargoes were imposed.
Due to its mineral and oil wealth, Southeast Asia became a goal for Japan. They were aware that such an invasion would inevitably result in conflict with America. Months of unsuccessful negotiations between Tokyo and Washington led to the attack on Pearl Harbor. In order to prevent American interference in their plan to obtain the resources in countries in Southeast Asia, which Japan named the "Southern Resource Area," they determined to eliminate America's Pacific Fleet.
