India, April 10 -- The Philippines unveiled a major coast guard base Thursday on an island in the South China Sea to serve as a "steadfast sentinel of our sovereignty" in a disputed region closely guarded by China's forces.

Chinese officials did not immediately react to the Philippines' opening of its coast guard district command on Thitu Island, which has been occupied by Filipino forces and civilians for decades but is also claimed by Beijing.

Chinese coast guard and other Government-linked ships frequently patrol outlying waters off the island, which is also claimed by Vietnam and Taiwan. Chinese and Filipino forces have had tense but mostly minor confrontations in outlying waters in the past.

China claims virtually the entire sea, ...