In 1945, towards the end of World War II, the U.S. Army and Marine Corps invaded Okinawa with 185,000 troops; a third of the civilian population was killed. After the war, Okinawa became a de facto trustee of the U.S. government, which established several military bases there and on other Ryukyu islands. In addition, the U.S. Civil Administration of the Ryukyu Islands altered the currency and culture of the region, causing tensions between native Ryukyuans and U.S. officials.
In 1960 the U.S.-Japan Security Treaty was signed, which stipulated that the U.S. would come to Japan’s aid should it be attacked. In turn, the Japanese allowed more access to base and ports for the U.S., provided that the U.S. government confer with the Japanese regarding any significant military action. The treaty was up for renewal in 1970. However, in the years preceding renewal, Japanese officials began to pressure the United States to return the Ryukyu Islands to Japan. The possibility that the Japanese might not renew the Security Treaty if the reversion was not addressed gave Tokyo additional leverage and made the Ryukyu Islands a pressing issue for Washington. Read more