(Bloomberg) -- The Philippines and the US resumed joint patrols in the South China Sea on Tuesday, years after they were halted, amid heightened tensions with Beijing over the disputed waters.

Philippine President Ferdinand Marcos Jr. announced the start of maritime and air patrols between the Southeast Asian nation’s military and the US Indo-Pacific Command in a post on X, formerly Twitter. The joint patrols will begin near the Philippines’ northernmost Batanes province that is close to Taiwan and will end in the South China Sea, Manila’s military said in a statement.

The activity, scheduled to run until Thursday, is a “significant initiative” and a “testament to our commitment to bolster the interoperability of our military forces,” Marcos said.

China’s Foreign Ministry spokeswoman Mao Ning said at a regular press briefing on Wednesday in Beijing that the joint Philippines and US patrols “should not undermine China’s territorial sovereignty and maritime rights and interests.”

The patrols take place just days after Marcos, during a US trip, warned that the situation in the South China Sea has “become more dire,” saying Beijing’s military buildup in the contested sea is getting closer to the Philippines’ coastline.

“Through collaborative efforts, we aim to enhance regional security and foster a seamless partnership with the United States in safeguarding our shared interests,” Marcos said on Tuesday.

Manila and Washington agreed to restart the joint South China Sea patrols in February after former President Rodrigo Duterte, who forged closer ties with Beijing, suspended them in 2016. 

Beijing claims nearly the entire South China Sea, including areas Manila says are part of its exclusive economic zone. Brunei, Malaysia, Vietnam, and Taiwan also lay claims over the waterway.

The resumption of the US and Philippine joint patrols comes amid heightened tensions in contested waters, including last month’s collision between Philippine and Chinese vessels. It also underlines the two countries’ reinvigorated defense alliance under Marcos, who early this year granted the US military access to more Philippine bases including one near Taiwan.

--With assistance from Allen Wan.

(Added Chinese Foreign Ministry’s comment in fourth paragraph)

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