The Japanese government has criticized China for installing a buoy in the high seas over Japan's continental shelf in the Pacific Ocean without adequate explanation.
"It is regrettable that a buoy was placed without providing details of its purpose," Chief Cabinet Secretary Yoshimasa Hayashi told a news conference Friday, referring to the object set up by a Chinese marine research vessel in the waters north of Okinotorishima, Japan's southernmost island.
Japan will continue to collect and analyze information, he added.
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