NHK analysis: China Coast Guard's giant ship more active in East China Sea

NHK has learned that one of the China Coast Guard's largest vessels has been increasingly sailing near the median line between Japan and China in the East China Sea while transmitting its location data.

The Japan Coast Guard is closely monitoring the situation in the waters, where Beijing apparently aims to assert its presence through what some experts regard as "demonstrative action."

The "China Coast Guard 2901" is based at a port in Zhejiang Province. The vessel is 165 meters long, has a displacement of about 10,000 tons, and carries a 76-millimeter cannon.

NHK's analysis of data from the Automatic Identification System, or AIS, for the last five years suggests the vessel has been more assertive in the area over the past two years.

The analysis confirms that the vessel has sometimes crossed the median line. It has also frequently sailed near areas which China has been unilaterally developing as gas fields, despite a 2008 agreement between Tokyo and Beijing on joint development.

The vessel has also been found to have sailed east of Dongyin Island, which is effectively controlled by Taiwan, in February this year. It came as close as 80 kilometers to the Senkaku Islands in Japan's Okinawa Prefecture in April. It sent out its location data in both areas.

Japan controls the Senkaku Islands. The Japanese government maintains the islands are an inherent part of Japan's territory. China and Taiwan claim them.

Chinese media reported that President Xi Jinping visited the vessel's command office last November. Xi reportedly received reports directly from crew members sailing in the East China Sea via video link, and gave instructions on strengthening law enforcement capabilities.

Sources say Beijing is believed to be aiming to enhance its presence in the East China Sea, including around the Senkaku Islands. They say it appears to be gauging Japan's responses as it continuously sails one of its coast guard's most prominent vessels in the waters.