Treaty of Mutual Cooperation and Security between the United States and Japan
The Treaty of Mutual Cooperation and Security between the United States and Japan, more commonly known as the U.S.–Japan Security Treaty in English and as the Anpo jōyaku or just Anpo in Japanese, is a treaty that permits the presence of U.S. military bases on Japanese soil, and commits the two nations to defend each other if one or the other is attacked "in the territories under the administration of Japan". Over time, it has established a military alliance between the United States and Japan.