HONG KONG, Sept. 26 (UPI) -- For some time China has been constructing large-scale underground nuclear submarine facilities on its southern island province of Hainan. At the same time, the Chinese People's Liberation Army navy and air force have dramatically reinforced their military structures on the Xisha Islands -- known in the West as the Paracel Islands -- located in the South China Sea off the coast of Vietnam.

The largest military airport in the South China Sea and a super signal and intelligence monitoring station already have been completed on the islands. Recent satellite photos show that the antennas of this intelligence station and related facilities occupy almost the whole of a small island adjacent to Woody Island, where the airport is located. An artificial causeway has been constructed to connect these two islands.

The photos show the smaller island dotted with a mass of radar antennas. Several large vertical high-frequency monitoring antennas are in evidence, which could cover virtually the whole of the South China Sea, all the territory of Vietnam and the Philippines and even high-frequency signals from Malaysia. In addition, there are at least two radar signal detectors and receivers.

Alongside these antennas, four bungalow-shaped structures have been built, apparently used for recording and processing signal intelligence. Judging from the types of antennas deployed on this island, it is clear that they are used for the acquisition of both radio and radar wave intelligence.

The immense scale of these listening facilities suggests that this base is most likely under the jurisdiction of the No. 3 and No. 4 Departments under the People's Liberation Army Headquarters of the General Staff.