The Philippines is using a recently installed Japanese-made air-surveillance radar system to monitor activity off its coast. It says it will share data from the radar with Tokyo to strengthen their security relationship.

Officials from Japan's defense ministry attended a handover ceremony at a Philippine Air Force base on Wednesday. The base faces the South China Sea, where the Philippines is involved in several territorial disputes with China.

"The transfer of this radar system signifies that the Philippines now has a new eye towards its surrounding airspace with Japanese-made equipment, solidifying the evidence of our cooperation," said Japanese defense ministry official Nishiwaki Osamu.

"We are cooperating because we have shared values against the contrived and unilateral attempt by other countries to appropriate the West Philippine sea as its own," added Philippine defense secretary Gilberto Teodoro. He avoided mentioning specific countries in his comments, but warned against illegal activities in the South China Sea.

The Philippines plans to install three more Japanese-made radar systems.

Tensions between the Philippines and China in the South China Sea are intensifying. The two countries have recently traded barbs over incidents involving their vessels in disputed waters.