The catalyst for the radicalization of Japanese universities was the Japan-U.S. Security Treaty signed on September 8, 1951 in San Francisco and renewed on January 19, 1960 in Washington. In Japan, the treaty is known as “ANPO” (an abbreviation of “Anzen Hosho Joyaku” = security guarantee treaty). The US was allowed to maintain military bases in Japan and Okinawa was to remain under American control until 1972. The 260,000 U.S. troops in Japan could use the bases for action in Asia without consulting the Japanese government. The U.S.  had jurisdiction over American personnel who committed crimes in Japan. The treaty could be ended only by mutual consent. Both right and left bitterly attacked the treaty, as it subordinated Japanese foreign policy to that of the U.S.  and it seemed like a return to the unequal treaties imposed on Japan in the nineteenth century, Yoshida Shigeru managed to secure its passage through the Diet (parliament) but there was a major crisis when it was revised and renewed in 1960, in spite of U.S.  service personal being subject to Japanese law. Opposition members of the Diet staged a sit-in to delay ratification and there was unprecedented popular opposition, with a series of huge strikes and violent demonstrations by workers and students. On June 15, hundreds were injured when police attacked students who had invaded the Diet. When the bill was passed the Prime Minister, Kishi Nobusuke, resigned and the opposition lost its impetus, yet this had been the most severe upheaval in postwar Japan.