Japan's first contact with the Western world came in 1542 when a Portuguese ship landed on its shore. During the 17th century, Japan saw traders and missionaries from Portugal, the Netherlands, England and Spain. Suspecting those traders and missionaries were forerunners of a military conquest by European powers, Japan's shogunate (military dictatorship) put more and more restrictions on the foreigners. This resulted in an isolation policy that lasted for 200 years, until Commodore Matthew Perry of the U.S. Navy negotiated the opening of Japan to the West with the Convention of Kanagawa in 1854. Within several years, renewed contact with the West profoundly altered Japanese society. The shogunate resigned, and the emperor was restored to power. The "Meiji restoration" of 1868 initiated many reforms. The feudal system was abolished, and numerous Western institutions were adopted, including a Western legal and educational system and constitutional government along parliamentary lines. However, parliamentary government was not rooted deeply enough to withstand the economic and political pressures of the 1930s, during which military leaders became increasingly influential. As a result, Japan withdrew from the League of Nations in 1933 and allied itself with Germany during World War II. Japan started a full scale of invasion of China in 1937 after its invasion of Manchuria in 1931 and attacked the United States at Pearl Harbor, Hawaii, on Dec. 7, 1941. In August 1945, the United States dropped two atomic bombs on Japan's Hiroshima and Nagasaki. On Sept. 2, 1945, the country surrendered to the United States aboard the USS Missouri in Tokyo Harbor. After the war, Japan was placed under international control of the Allies to ensure that it would become a peaceful nation and establish a democratic government. Political, economic, and social reforms were introduced, and the country's constitution took effect on May 3, 1947. The United States and 45 other Allied nations signed the Treaty of Peace with Japan in September 1951. The post-World War II years saw tremendous economic growth in Japan driven by a high rate of investment and efficient industrial techniques. Today, Japan is the second-largest economy in the world. Although the economy experienced a major slowdown starting in the 1990s following three decades of unprecedented growth, Japan still remains a major economic power, both in Asia and globally.