YONAGUNI, Japan - Japan began its first military expansion at the western end of its island chain in more than 40 years on Saturday, breaking ground on a radar station on a tropical island off Taiwan.
The move risks angering China, locked in a dispute with Japan over nearby islands which they both claim.
Japanese Defence Minister Itsunori Onodera, who attended a ceremony on Yonaguni island to mark the start of construction, suggested the military presence could be enlarged to other islands in the seas southwest of Japan's main islands. "This is the first deployment since the US returned Okinawa (1972) and calls for us to be more on guard are growing," Onodera told reporters. "I want to build an operation able to properly defend islands that are part of Japan's territory."
The military radar station on Yonaguni, part of a longstanding plan to improve defence and surveillance, gives Japan a lookout just 150 km (93 miles) from the Japanese-held islands claimed by China.
Building the base could extend Japanese monitoring to the Chinese mainland and track Chinese ships and aircraft circling the disputed crags, called the Senkaku by Japan and the Diaoyu by China.
The 30 sq km (11 sq mile) Yonanguni is home to 1,500 people and known for strong rice liquor, cattle, sugar cane and scuba diving. Prime Minister Shinzo 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.
The new base "should give Japan the ability to expand surveillance to near the Chinese mainland," said Heigo Sato, a professor at Takushoku University and a former researcher at the Defence Ministry's National Institute for Defence Studies. "It will allow early warning of missiles and supplement the monitoring of Chinese military movements."
Japan does not specify an exact enemy when discussing its defence strategy but it makes no secret it perceives China generally as a threat as it becomes an Asian power that could one day rival Japan's ally in the region, the United States.
Japan, in its National Defence Programme Guidelines issued in December, expressed "great concern" over China's military buildup and "attempts to change the status quo by coercion" in the sea and air.