One of the main causes for the attack on Pearl Harbor was Japan's ambition for expansion in the Pacific. Japan wanted to gain access to more natural resources, such as oil and steel; however, this was impossible without expanding to and conquering Southeast Asia, specifically Malaya and the Dutch East Indies. In 1949, the US president, Franklin D. Roosevelt, ordered for the US fleet to be moved from California to Pearl Harbor, which basically stopped Japan from expanding their control and influence in the Pacific.
Japan and the US stopped all economic and business collaborations, and many officials and politicians from both sides were convinced that a conflict was inevitable and all that was left was to expect an attack. Thus, on December 7th, 1941, in the hopes of weakening the US navy and gaining the upper hand, the Imperial Japanese Navy Air Service attacked the US naval base and the Pacific Fleet at Pearl Harbor.
The Japanese Army destroyed around twenty American ships (eight battleships) and more than 250 airplanes; nearly 2,500 people died, and around 1,000 people were injured. The attack is what forced America to enter the Second World War, as until then, the US was a neutral country; immediately after the attack, America declared war on Japan. Considering the damage that was caused, many think that Pearl Harbor was a successful attack; however, it was not a strategic success, as nothing changed for Japan. The country wasn't able to fulfill its aspirations to expand further in the Pacific, and the US still refused to do business with Japan.