United States-Japan Treaty of Mutual Cooperation and Security

The United States-Japan security alliance rests on a U.S. defence commitment to respond if Japan is subjected to an armed attack in territories under its administration. The treaty combines this pledge with Japan's provision of facilities for United States forces, creating a continuing framework for deterrence, consultation and regional security.

Core security commitment

Under Article V, each party recognizes that an armed attack against either party in territories under the administration of Japan would endanger its own peace and safety. Each promises to act against the common danger in accordance with its constitutional provisions and processes.

• The commitment is reciprocal in wording but geographically limited to territories administered by Japan.
• It is not an automatic declaration of war because each party must act through its respective constitutional procedures.

Military presence and consultation

Under Article VI, Japan grants the United States the use of facilities and areas for its land, air and naval forces. This U.S. forward military presence supports Japan's security and gives operational credibility to the defence commitment.

• Under Article IV, the parties consult on treaty implementation and whenever Japan's security or regional peace and security are threatened.
• Detailed arrangements concerning facilities and their use are governed through a separate status agreement.

Treaty framework and duration

The present treaty was signed on 19 January 1960 and entered into force on 23 June 1960, replacing the earlier post-war security arrangement. Under Article X, it continued after an initial ten-year period and may be terminated by either party after giving one year's notice.