Japan was at war with China.
Despite being a military superpower, their war with China was using up their resources. During that time, most of their resources especially oil were coming from the US. The US did not approve of Japanese aggression in China and they declared an embargo on Japan. This means they would stop supplying Japan with raw materials. So where would Japan get their resources to continue the war now? The Japanese High Command carefully discussed this and came up with the conclusion that the Dutch East Indies would be the best place to gain resources. But they knew that an attack on the Dutch East Indies would probably bring the US into the war.
So they had to find a way to prevent the US from fighting with them until they conquered the Dutch East Indies. That’s when they planned Pearl Harbor. The goal of Pearl Harbor was to disable the American fleet for a few months to give them enough time to conquer the Dutch East Indies and to absorb its resources to finance their war in China and the US once the US’ navy was rebuilt. The Japanese were tired of negotiations with the United States. They wanted to continue their expansion within Asia but the United States had placed an extremely restrictive embargo on Japan in the hopes of curbing Japan’s aggression. Negotiations to solve their differences hadn’t been going well. Rather than giving in to U.S.
demands, the Japanese decided to launch a surprise attack against the United States in an attempt to destroy the United States’ naval power even before an official announcement of war was given. The Japanese practiced and prepared carefully for their attack on Pearl Harbor. They knew their plan was extremely risky. The probability of success depended heavily on complete surprise. On November 26, 1941, the Japanese attack force, led by Vice Admiral Chuichi Nagumo, left Etorofu Island in the Kurils (located northeast of Japan) and began its 3,000-mile journey across the Pacific Ocean.
Sneaking six aircraft carriers, nine destroyers, two battleships, two heavy cruisers, one light cruiser, and three submarines across the Pacific Ocean was not an easy task. Worried that they might be spotted by another ship, the Japanese attack force continually zig-zagged and avoided major shipping lines. After a week and a half at sea, the attack force made it safely to its destination, about 230 miles north of the Hawaiian island of Oahu. On the morning of December 7, 1941, the Japanese attack on Pearl Harbor began. At 6:00 a.m., the Japanese aircraft carriers began launching their planes amid rough sea.
In total, 183 Japanese aircraft took to the air as part of the first wave of the attack on Pearl Harbor. At 7:15 a.m., the Japanese aircraft carriers, plagued by even rougher seas, launched 167 additional planes to participate in the second wave of the attack on Pearl Harbor.
The first wave of Japanese planes reached the U.S. Naval Station at Pearl Harbor (located on the south side of the Hawaiian island of Oahu) at 7:55 a.m. on December 7, 1941. Just before the first bombs dropped on Pearl Harbor, Commander Mitsuo Fuchida, leader of the air attack, called out, “Tora! Tora! Tora!” (“Tiger! Tiger! Tiger!”), a coded message which told the entire Japanese navy that they had caught the Americans totally by surprise.