A satellite image released by the Asian Maritime Transparency Initiative at Washington's Center for Strategic and International Studies shows construction of possible radar tower facilities in the Spratly Islands in the disputed South China Sea in this image released on Feb. 23, 2016. REUTERS

The United States, India and Japan are to hold naval drills off the northern coast of the Philippines near the disputed South China Sea this year to reinforce a “freedom of navigation” doctrine, amid China’s expansion in the sea region that has alarmed neighbors, officials said.

The drills, the dates of which have not been announced, are part of annual exercises between the U.S. and Indian navies that last year expanded to include Japan, another country that has also raised concern over China’s muscle flexing in the region.

The U.S. Pacific Command chief, Adm. Harry B. Harris, said the exercises were scheduled in the northern Philippine Sea, stressing that unimpeded sea travel was a right that must be enjoyed by all nations.

“While some countries seek to bully smaller nations through intimidation and coercion, I note with admiration India’s example of peaceful resolution of disputes with your neighbors in the waters of the Indian Ocean,” Harris said Wednesday in India, Reuters reported.

He said the U.S. also wanted to expand annual drills with India -- called Malabar -- into joint operations such as sea patrols across Asia Pacific in a bid to counterbalance China. This could, however, potentially draw India into the territorial row amid warnings from Beijing it could be viewed as interference, the report said.

But Harris insisted that “no nation should perceive freedom of navigation operations as a threat,” the Wall Street Journal said.

China, which claims the whole of the South China Sea, is locked in an increasingly tense territorial dispute with smaller Asian neighbors over islands and atolls that straddle key shipping lanes and are believed to hold vast, untapped mineral resources. Other claimants are Brunei, Malaysia, Vietnam and Taiwan.

China has been on a building spree, constructing land features in islands it claims, carrying overflights and reportedly sending surface-to-air missiles to be stationed there. Vietnam has protested the installation of missiles in the Paracel island, which it claims, and has called for more U.S. involvement in the sea region.

Amid the territorial wranglings, the U.S. had sent warships to test "freedom of navigation operations" in the region, and called for a freeze on China's construction in the islands. It had also donated two decommissioned ships to its former colony, the Philippines, which this week also bagged a agreement to receive military equipment from Japan.

But joint maneuvers come amid reports that China was ramping up its defense program, having confirmed earlier this year that it may launch a fully domestically made aircraft carrier soon.