When Chinese military vessels sail to the waters near the Senkaku Islands (Ishigaki City, Okinawa Prefecture) to replace the ships on duty, they sail with their radars turned off so that the Self-Defense Forces and the U.S. military cannot detect their movements, government sources revealed on March 29. This is thought to indicate that China is beefing up activities based on a scenario of actual battle. This is linked to the China Coast Guard vessels that have been repeatedly intruding into Japan’s territorial waters around the Senkakus. The Ministry of Defense is strengthening its vigilance and surveillance activities.
According to government sources, Chinese military vessels sailing in waters near the 27th parallel north, which is about 90 km north of the Senkaku Islands, are engaging in activities that simulate wartime. Two Chinese vessels are in these waters at all times, and it is believed that the Chinese Coast Guard vessels operating around the Senkaku Islands are making preparations in the event of an unforeseen situation. Vessels are not permanently stationed in the waters; rather, the vessels swap off with other ships at certain intervals.
For the past two or three years, Chinese military ships heading for these waters have been sailing with their surface-search and air-search radars off from the time they leave port. After arriving in the waters, the radars are activated for warning and surveillance purposes.
Sailing without radar is dangerous as it increases the possibility of collisions with fishing boats and commercial ships. According to government sources, vessels may choose to sail with radars off in an emergency, but it is extremely unusual to do this during peacetime. The Self-Defense Forces and the U.S. military identify warships by means of radar waves, and these movements by Chinese military ships are thought to be aimed at harassing Japan and the United States. Some say that it is intended to prevent Japan and the United States from gaining a full picture of the Chinese Navy by making it difficult for them to ascertain the rotation of Chinese military ships in waters near the 27th parallel north.
Also, it is said that some Chinese military ships are using Japanese-made radars designed for commercial ships. This may also be a measure to prevent the vessels from being identified.
The Self-Defense Forces and the U.S. military use radar waves to identify Chinese vessels and use reconnaissance satellites to monitor movements. However, there are times when orbiting reconnaissance satellites cannot ascertain the movements of Chinese military ships in the East China Sea, and the Chinese side apparently seems to be targeting these time periods to dispatch vessels. The government is under pressure to further strengthen vigilance and surveillance.