The patrol comes less than a week after Philippine President Ferdinand Marcos Jnr signed the Maritime Zones Act and Archipelagic Sea Lanes Act, embedding Manila’s claims to the South China Sea in domestic law. The US expressed its support for the Philippine legislation, saying other countries had passed similar laws.

China has held sea and air combat drills at disputed Scarborough Shoal, an uninhabited area of reefs and rocks it had seized from the Philippines in the South China Sea.

The ongoing territorial disputes in the South China Sea, China conducted intensive sea and air combat drills near the contentious Scarborough Shoal on Wednesday. This area—an expanse of reefs and rocks west of the Philippines’ Luzon Island—has been a persistent flashpoint in China-Philippines relations since China seized control of the shoal in 2012.

China declared its maritime baselines around Scarborough Shoal after the Philippines passed laws defining its maritime zones and sea lanes last week.

The move was a direct response to the Philippines’ enactment of two new laws aimed at strengthening the country’s own maritime claims.

The Philippines has protested China’s baselines around the disputed Scarborough Shoal, as tensions between the two nations build up anew over their competing claims in the South China Sea.