BEIJING China's defense ministry said on Thursday it will continue military patrols in waters near a tropical Japanese island close to Taiwan, days after Tokyo announced it would break ground on a new radar base in the area.
The radar station on Yonaguni Island, just 150 km (93 miles) from a group of disputed islands in the East China Sea, marks Japan's first military expansion at the western end of its island chain in more than 40 years.
"We are playing close attention to Japan's relevant military trends," Defence Ministry spokesman Yang Yujun said in comments posted on the ministry's website.
"China's military will continue to carry out battle readiness patrols, military drills and other activities in the relevant area," Yang said.
Plans for the new base, which could extend Japan's monitoring capability up to the Chinese mainland, come as relations between Tokyo and Beijing have deteriorated due to the row over the islands and Japanese Prime Minister Shinzo Abe's visit to the controversial Yasukuni Shrine, where Japanese war criminals are honored among the country's war dead.
China's ties with Japan have long been colored by what Beijing considers Tokyo's failure to atone for its brutal wartime occupation of parts of the country.
China's modernizing navy, and its increasingly assertive stance on what it sees as its sovereign maritime territory in the East China and South China Seas, has sparked nervousness from other countries in the region - particularly Japan.
The 30 sq km (11 sq mile) Yonaguni is home to 1,500 people and known for strong rice liquor, cattle, sugar cane and scuba diving. Abe's decision to put troops there shows Japan's concerns about the vulnerability of its thousands of islands and the perceived threat from China.
U.S. President Barack Obama assured ally Japan on Thursday during a state visit there that Washington was committed to its defence, but denied he had drawn any new "red line" and urged peaceful dialogue with China over the islands, called Senkaku in Japanese and Diaoyu in Chinese.
(Reporting by Michael Martina; Editing by Michael Perry)