The U.S. Navy is routinely flying P-3 Orion surveillance aircraft over waters claimed by both the Philippines and China and is providing its intelligence to Manila, according to comments made Wednesday by Foreign Secretary Albert del Rosario.

“We do have an interest in terms of what is going on with our exclusive economic zone, within our continental shelf, and we want to know if there are any intrusions,” del Rosario told reporters at a press conference in the Philippine capital, according to Agence France Presse.

The U.S. has been monitoring Chinese maritime activity for years as the Middle Kingdom ramps up efforts to become a major blue-water power in Asia, a prospect that has Southeast Asia and India concerned about future conflicts as China’s influence spreads from its shores south to the Indian Ocean.

Chinese President Xi Jinping on Wednesday said during an address to his politburo in Beijing that China was willing to resolve territorial disputes peacefully, but he couched his language in terms of protecting China’s sovereignty and defense interests.

“China will prepare to cope with complexities, enhance its capacity in safeguarding maritime rights and interests, and resolutely safeguard its maritime rights and interests,” said Xi said, according to Reuters. “The oceans and seas have an increasingly important strategic status concerning global competition in the spheres of politics, economic development, military, and science and technology.”

China claims virtually all of the waters in the South China Sea, which has created considerable tensions with Southeast Asian states, especially Vietnam and the Philippines. The Philippines, comprised of thousands of islands between Taiwan and Indonesia, has petitioned the U.S. to back its opposition to Chinese claims.

In addition to military interests, China could be setting its sights on resources claimed by coastal states.  

“While the value of oil and gas resources in the SCS [South China Sea] remains the subject of debate, the potential value of its fishery and aquaculture resources is not in doubt. Currently, the SCS accounts for one-tenth of the world's global fisheries catch, and plays host to a multibillion-dollar fishing industry,” said an editorial published Tuesday in the Bangkok Post.  

Japan has its own issues with China in the East China Sea, over the Senkaku/Diaoyu islands, tensions that flared up late last year and led to street protests and boycotts of Japanese goods in China.