Title: Japan–United States relations
Content:  War caused the United States to cut off the oil and steel Japan required for their military conquests. Japan responded with attacks on the Allies, including the surprise attack on Pearl Harbor on December 7, 1941, which heavily damaged the US naval base at Pearl Harbor, opening the Pacific theater of World War II. The United States made a massive investment in naval power and systematically destroyed Japan's offensive capabilities while island hopping across the Pacific. To force a surrender, the Americans systematically bombed Japanese cities, culminating in the atomic bombings of Hiroshima and Nagasaki in August 1945. Japan surrendered, and was subjected 
Title: History of Japan
Content:   In late 1941, Japan's government, led by Prime Minister and General Hideki Tojo, decided to break the US-led embargo through force of arms. On December 7, 1941, the Imperial Japanese Navy launched a surprise attack on the American fleet at Pearl Harbor, Hawaii. This brought the US into World War II on the side of the Allies. Japan then successfully invaded the Asian colonies of the United States, the United Kingdom, and the Netherlands, including the Philippines, Malaya, Hong Kong, Singapore, Burma, and the Dutch East Indies. In the early stages of the war, Japan scored victory after victory. The tide began to turn against Japan following the Battle of Midway in June 1942 and the subsequent Battle of Guadalcanal, in which Allied troops wrested the Solomon Islands from Japanese 
Title: Japan–United States relations
Content:  Japan attacked the American navy base at Pearl Harbor, Hawaii, on December 7, 1941. In response, the United States declared war on Japan. 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 conflict was a bitter one, marked by atrocities such as the executions and torture of American prisoners of war by the Imperial Japanese Army and the desecration of dead Japanese bodies. Both sides interred enemy aliens. Superior American military production supported a campaign of island-hopping in the Pacific and heavy bombardment of cities 
Title: Attack on Pearl Harbor
Content:  War between Japan and the United States had been a possibility that each nation had been aware of, and planned for, since the 1920s. Japan had been wary of American territorial and military expansion in the Pacific and Asia since the late 1890s, followed by the annexation of islands, such as Hawaii and the Philippines, which they felt were close to or within their sphere of influence. Although Japan had begun to take a hostile policy against the United States after the rejection of the Racial Equality Proposal, the relationship between the two countries was cordial enough that they remained trading partners. Tensions did not seriously grow until 
Title: Japan during World War II
Content:  Before Pearl Harbor the Japanese had already begun imperial expansion in Manchuria (1931), Inner Mongolia (1936), Jehol (1933), China (1937), and in other territories and islands during World War 1. The Empire of Japan entered World War II on 27 September 1940 by signing the Tripartite Pact with Germany and Italy, and the Japanese invasion of French Indochina, though it wasn't until the attack on Pearl Harbor on 7 December 1941 that the U.S. entered the conflict. Over the course of seven hours there were coordinated Japanese attacks on the U.S. -held Philippines, Guam and Wake Island, the Dutch Empire in the Dutch East Indies, Thailand and on the British Empire in Borneo, Malaya and Hong Kong. The strategic goals of the offensive were to cripple the U.S. Pacific fleet, capture oil fields in the Dutch East Indies, and maintain their sphere of influence of China, East Asia, and also Korea. It was also to expand the outer reaches of the Japanese Empire to create a formidable defensive perimeter around newly acquired territory.
Title: History of Japan
Content:  a subject of controversy, with various historians portraying him as either a powerless figurehead or an enabler and supporter of Japanese militarism. The United States opposed Japan's invasion of China and responded with increasingly stringent economic sanctions intended to deprive Japan of the resources to continue its war in China. Japan reacted by forging an alliance with Germany and Italy in 1940, known as the Tripartite Pact, which worsened its relations with the US. In July 1941, the United States, the United Kingdom, and the Netherlands froze all Japanese assets when Japan completed its invasion of French Indochina by occupying the southern half of the country, further increasing tension in the Pacific.
Title: Japanese declaration of war on the United States and the British Empire
Content:  The document declares the war against the United States and British Empire, discusses their presumed disruptive actions against Japan's foreign policy and states that all avenues for averting war have been exhausted from the Government of Japan. Japan had invaded much of East Asia to create what they called the "Greater East Asia Co-Prosperity Sphere", now largely viewed as a pretext for imperialism. In response, the US imposed an oil embargo on Japan in August 1941 to stop aiding their aggression in Asia and to contain Japanese actions such as their war crimes in Nanking. There was also an embargo on steel. Japan saw this as a hostile and provocative act, and retaliated with the bombing of Pearl Harbor and the declarations of war on the US and the British Empire.
Title: Naval history of Japan
Content:   In the years before World War II the IJN began to structure itself specifically to fight the United States. A long stretch of militaristic expansion and the start of the Second Sino-Japanese War in 1937 had alienated the United States, and the country was seen as a rival of Japan. To achieve Japan’s expansionist policies, the Imperial Japanese Navy also had to fight off the largest navies in the world (The 1922 Washington Naval Treaty allotted a 5/5/3 ratio for the navies of Great Britain, the United States and Japan). She was therefore numerically inferior and her industrial base for expansion was limited (in particular compared to the United States). 
Title: Japan during World War II
Content:  United States naval base in Hawaii, thereby bringing the United States to World War II on the side of the Allies. On September 4, 1941, the Japanese Cabinet met to consider the war plans prepared by Imperial General Headquarters, and decided: "Our Empire, for the purpose of self-defense and self-preservation, will complete preparations for war ... and is ... resolved to go to war with the United States, Great Britain, and the Netherlands if necessary. Our Empire will concurrently take all possible diplomatic measures vis-a-vis the United States and Great Britain, and thereby endeavor to obtain our objectives ... In the event that there is no prospect of our demands being met by the 
Title: Japan–United States relations
Content:   During World War I, both nations fought on the Allied side. With the cooperation of its ally the United Kingdom, Japan's military took control of German bases in China and the Pacific, and in 1919 after the war, with U.S. approval, was given a League of Nations mandate over the German islands north of the equator, with Australia getting the rest. The U.S. did not want any mandates. Japan's aggressive approach in its dealings with China, however, was a continual source of tensionindeed eventually leading to World War II between the two nations. Trouble arose between Japan on the one hand and China, Britain and the U.S. on the other 

Question: what started the war between us and japan?
Answer: attack on Pearl Harbor.