The Philippines launched joint sea and air patrols with the U.S. military. According to officials from the Southeast Asian country, the U.S. and Philippine militaries began conducting combined patrols in the waters close to Taiwan on Tuesday. This development is expected to exacerbate tensions with China.

This year, the treaty partners’ security cooperation has increased dramatically. They decided to nearly triple the number of Philippine facilities the U.S. military may access, some of which face Taiwan. They held their biggest-ever combined military exercise in April.

Philippine President Ferdinand Marcos Jr. said this week’s three-day combined air and sea exercise was a “significant initiative” to improve interoperability.

He stated on social media platform X, “I am confident this will contribute to a more secure and stable environment for our people.”

The northernmost tip of the Philippines, Mavulis Island, is roughly 100 kilometers (62 miles) off the coast of Taiwan. According to Northern Luzon command spokesperson Eugene Cabusao, this is where the practice will begin.

It will terminate at the West Philippine Sea, which Manila refers to as its exclusive economic zone (EEZ) when referring to South China Sea waters.

The U.S. would send a littoral combat ship and a P8-A maritime patrol and surveillance aircraft, according to the Philippine military, which also claimed that three navy boats, two FA-50 light combat aircraft, and an A-29B Super Tucano light attack bomber would take part.

Marcos informed a forum in Hawaii one day earlier that the South China Sea situation had gotten more “dire” and that the Chinese military was approaching the Philippine coast.

The patrols, which are sure to annoy China, indicate that the Philippines is strengthening its defense in response to China’s “aggressive activities” in the highly crucial waterways, which it has long considered a possible flashpoint between the U.S. and China.

China’s embassy in Manila did not immediately answer an inquiry about the exercise.

China bases its claim to the majority of the South China Sea on a “nine-dash line” that penetrates the exclusive economic zones (EEZs) of rival claimants Brunei, Indonesia, Malaysia, the Philippines, and Vietnam and extends up to 1,500 km (900 miles) south of China’s mainland.

After a tense relationship with former President Rodrigo Duterte, who had shifted closer to Beijing in exchange for investments and infrastructure projects, Marcos has developed stronger relationships with Washington since taking office last year.

Under Marcos, relations with China have deteriorated due to recurrent standoffs between Chinese and Filipino warships in waters that both nations claim, which have sparked contentious rhetorical exchanges and raised fears of escalation.

To ease tensions, Marcos recently met with President Xi Jinping of China.

According to Jay Batongbacal, director of the Institute for Maritime Affairs and Law of the Sea in Manila, the capital, during the joint patrol with the United States, it was demonstrated that Manila was taking a position over the South China Sea.

“It shows that the Philippines is firming up its posture on West Philippine Sea issues,” Batongbacal stated.