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Japan considers floating islands as Aegis Ashore missile system alternative: reports

A megafloat craft is seen in the Uraga Channel after departing from the Port of Yokohama on its way to Onahama Port in Fukushima Prefecture, in this May 15, 2011, file photo taken from a Mainichi Helicopter. (Mainichi/Takashi Morita)

TOKYO -- Floating islands equipped with missile defense systems are being discussed by the Japanese government as an alternative to the suspended surface-to-air Aegis Ashore missile program, it has emerged.

    In the past, use of megafloat structures has been proposed to help with works connected to moving the U.S. Marine Corps Air Station Futenma, in the city of Ginowan in Okinawa Prefecture, southernmost Japan, to the proposed site of a new base in nearby Henoko, in the city of Nago. But the idea was ultimately not pursued due to a number of issues including technological hurdles.

    Megafloats are made with methods based on shipbuilding technology, in which metal boxes are connected together and put out to float in the sea. Among their advantages are that they have shorter construction times compared to land reclamation, and they have a lower impact on the environment.

    The Aegis Ashore program, which was set to be installed in the northwestern prefecture of Akita and Yamaguchi Prefecture in west Japan, was suspended over concerns that the booster technology to propel the weapons could fall onto residential areas and other places. By having the technology launch from equipment floating over the Sea of Japan, it appears that safety issues would be solved.

    But it's unknown from a technological perspective whether the system could withstand bad weather and other variables. Artificial islands floating on the sea can also be approached by outside parties easily, and defending them is difficult. There are also issues including how to dispatch troops for security.

    Megafloats have seen use before, including in 2011 after the Great East Japan Earthquake, when they were successfully used to temporarily store low concentrations of polluted water generated by the resultant accident at the Tokyo Electric Power Co.'s Fukushima Daiichi Nuclear Power Station. But there are very few previous instances of the technology being used in Japan.

    When the now-dissolved Democratic Party of Japan was in power between 2009 and 2012, plans including one for a floating island runway in Nago had been scrapped. The majority of cases have ended with insurmountable issues being presented by technology and high construction costs, among other problems. A senior official at the Japan Self-Defense Forces said, "In recent years, damage from typhoons has been getting worse. If we were to make a floating island that could greatly withstand wind and waves, it's possible that costs would balloon."

    (Japanese original by Yusuke Tanabe, Political News Department)

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