spies. American occupation After World War II, the Supreme Commander of the Allied Powers allowed only the 129 islanders of Western origin to go back to Chichijima in recognition of their mistreatment by wartime Japan. Other houses on the island were destroyed. In 1960, the harbor facilities were devastated by tsunami after the Great Chilean earthquake. Several occupied islands, including Chichijima, were used by the United States in the 1950s to store nuclear arms, according to Robert S. Norris, William M. Arkin, and William Burr, writing for the Bulletin of the Atomic Scientists in early 2000. This is despite the Japanese Constitution being explicitly anti-war. Japan holds Three Non-Nuclear Principles. Modern Japan The island was returned to Japanese sovereignty in 1968. At that time, the "Westerner" islanders were allowed to choose either American or Japanese citizenship. Many of those who chose American citizenship are to this day allowed to regularly return to the island, where some run businesses during the summer tourist season. Topography and climate Chichijima is located at . Currently, around 2,000 people live on the island, and the island's area is about . On English maps from the early 19th century, the island chain was known as the Bonin Islands. The name Bonin comes from a French cartographer's corruption of the old Japanese word 'munin', which means 'no man', and the English translated it to "No mans land" islands. The climate of Chichijima is on the boundary between a tropical monsoon climate (Köppen Am), a tropical rainforest climate (Köppen Af), and a humid subtropical climate (Köppen Cfa). Temperatures are warm to hot and humid all year round, and have certainly remained between owing to the warm currents from the North Pacific gyre that surround the island. Rainfall is, however, less heavy than in most parts of mainland Japan, since the island is too far south to be influenced by the Aleutian Low and too far from mainland Asia to receive monsoonal rainfall or orographic precipitation on the equatorward side of the Siberian High. Occasionally, very heavy cyclonic rain falls, as on 7 November 1997, when the island received its record daily rainfall of and monthly rainfall of . Island development Astronomy and telemetry stations The Japanese National Institute of Natural Sciences (NINS) is the umbrella agency maintaining a radio astronomy facility on Chichijima. Since 2004, the National Astronomical Observatory of Japan (NAOJ) has been a division of