The United States and Japan After World War II

After suffering devastating casualties at each others' hands during World War II, the U.S. and Japan were able to forge a strong postwar diplomatic alliance. The U.S. State Department still refers to the American-Japanese relationship as "the cornerstone of U.S. security interests in Asia and . . . fundamental to regional stability and prosperity."

The Pacific half of World War II, which began with Japan's attack on the American naval base at Pearl Harbor, Hawaii, on December 7, 1941, ended almost four years later when Japan surrendered to American-led Allies on September 2, 1945. The surrender came after the United States had dropped two atomic bombs on Japan. Japan lost some 3 million people in the war.

Immediate Post-War Relations

The victorious allies put Japan under international control. U.S. General Douglas MacArthur was the supreme commander for the reconstruction of Japan. Goals for reconstruction were democratic self-government, economic stability, and peaceful Japanese co-existence with the community of nations.

The United States allowed Japan to keep its emperor — Hirohito — after the war. However, Hirohito had to renounce his divinity and publicly support Japan's new constitution.

Japan's U.S.-approved constitution granted full freedoms to its citizen, created a congress — or "Diet," and renounced Japan's ability to make war.

That provision, Article 9 of the constitution, was obviously an American mandate and reaction to the war. It read, "Aspiring sincerely to an international peace based on justice and order, the Japanese people forever renounce war as a sovereign right of the nation and the threat or use of force as a mean of settling international disputes.

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"In order to accomplish the aim of the preceding paragraph, land, sea, and air forces, as well as other war potential, will never be maintained. The right of belligerency of the state will not be recognized."

Japan's post-war constitution became official on May 3, 1947, and Japanese citizens elected a new legislature. The U.S. and other allies signed a peace treaty in San Francisco formally ending the war in 1951.

Security Agreement

With a constitution that would not permit Japan to defend itself, the U.S. had to take on that responsibility. Communist threats in the Cold War were very real, and U.S. troops had already used Japan as a base from which to fight communist aggression in Korea. Thus, the United States orchestrated the first of a series of security agreements with Japan.

Simultaneous with the San Francisco treaty, Japan and the United States signed their first security treaty. In the treaty, Japan allowed the United States to base army, navy, and air force personnel in Japan for its defense.

In 1954, the Diet began creating Japanese ground, air, and sea self-defense forces. The JDSFs are essentially part of local police forces due to the constitutional restrictions. Nevertheless, they have completed missions with American forces in the Middle East as part of the War on Terror.​

The United States also began returning parts of the Japanese islands back to Japan for territorial control. It did so gradually, returning part of the Ryukyu islands in 1953, the Bonins in 1968, and Okinawa in 1972.

Treaty of Mutual Cooperation and Security

In 1960, the United States and Japan signed the Treaty of Mutual Cooperation and Security. The treaty allows the U.S. to keep forces in Japan.

Incidents of American servicemen raping Japanese children in 1995 and 2008 led to heated calls for the reduction of American troop presence in Okinawa. In 2009, U.S. Secretary of State Hillary Clinton and Japanese Foreign Minister Hirofumi Nakasone signed the Guam International Agreement (GIA). The agreement called for the removal of 8,000 U.S. troops to a base in Guam.

Security Consultative Meeting

In 2011, Clinton and U.S. Secretary of Defense Robert Gates met with Japanese delegates, reaffirming the U.S.-Japanese military alliance. The Security Consultative Meeting, according to the State Department, "outlined regional and global common strategic objectives and highlighted ways to strengthen security and defense cooperation."

Other Global Initiatives

Both the United States and Japan belong to a variety of global organizations, including the United Nations, World Trade Organization, G20, World Bank, International Monetary Fund, and the Asia Pacific Economic Cooperative (APEC). Both have worked together on such issues as HIV/AIDS and global warming.