In 1639, the shogunate commenced the isolationist sakoku ("closed country") policy spanning two and a half centuries of feeble political unity known as the Edo period. (Frost, 25-7)
Late in the nineteenth century, abundance of the prerogative and the resignation of the shogunate led to the founding of a centralized state integrated under the name of the Emperor. Influenced by Western political, judicial and military institutions, the Cabinet prepared the Privy Council, brought in the Meiji Constitution, and assembled the Imperial Diet. This transformed the Empire of Japan into an industrialized world power that got into a number of military conflicts to increase the empire's sphere of authority. Today, Japan is a constitutional monarchy, with the powers of the Emperor being very limited. Seen as a ceremonial figurehead, the constitution defines him as "the symbol of the state and of the unity of the people". (NDL, 1) Power is chiefly vested in the Prime Minister of Japan and other elected members of the Diet, while Japanese people are the root of the sovereignty.
The relationships between U.S and Japan date back to the 1850's when Commodore Matthew Perry with his "Black Ships" sailed to Japan and signed the Convention of Kanagawa in order to initiate trade between Japan and U.S. This ended the sakoku policy of Japan and 300 year seclusion from the outside world. A few years later, the first Japanese embassy to the United States ever, was sent to ratify the new Treaty of Friendship, Commerce, and Navigation among the two regimes. Subsequent to the Meiji Restoration of 1867, the United States aided Japan in its modernization of its economy and of its military. This resulted in the new constitution of Japan being partly influenced by the United States Constitution. (Hay, 1)
Diplomatic relations ended with the Japanese attack on Pearl Harbor on December 7, 1941, drawing the United States into World War II. The war ended after the Atomic bombings of Hiroshima and Nagasaki in August 1945. After the end of the Second World War, Japan was taken under control by the Allied Powers, led by the United States. The San Francisco Peace Treaty, signed on September 8, 1951, manifested the end of the Allied occupation, and Japan regained its independence on April 28, 1952. The early post-occupation period Japan needed direct United States economic assistance. The general Japanese public feeling of dependence decreased gradually as the devastating results of World War II faded into the background and commercial activities with the United States saw a significant growth. (Huntington, 3-17)
Self-confidence increased as the country applied its assets and organizational skill to retrieve economic health. This led to a general want for greater autonomy from United States influence. Bilateral talks on improving the 1952 security pact started in 1959, and the new Treaty of Mutual Cooperation and Security was signed in Washington on January 19, 1960. The pact, when presented to the Diet for approval, stirred a bitter argument over the Japan-United States relationship and a violent all-out effort was made by the leftist opposition to thwart its passage. Under this treaty, both U.S and Japan assumed an obligation to aid each other in case of an armed attack on provinces under Japanese supervision. (LaFeber, 165)
It was however implicit, that Japan could not come to