US and Philippine troops began joint maritime and air patrols off the Southeast Asian country on Tuesday, President Ferdinand Marcos said, as the countries seek to counter China’s growing assertiveness in the region. The longtime treaty allies agreed in February to resume joint patrols in the disputed South China Sea, which Beijing claims almost entirely. They had suspended maritime patrols in the hotly contested area under the rule of former president Rodrigo Duterte, who favoured Beijing over Washington. Marcos, who has sought to repair relations with the United States since taking office in 2022, said the patrols would be held over three days. “This significant initiative is a testament to our commitment to bolster the interoperability of our military forces in conducting maritime and air patrols,” Marcos said in a statement. “Through collaborative efforts, we aim to enhance regional security and foster a seamless partnership with the United States in safeguarding our shared interests.” The Philippine military said the “maritime cooperative activity” with the US Indo-Pacific Command would start near the coastal province of Batanes and end in the West Philippine Sea. Manila refers to South China Sea waters immediately west of the Philippines as the West Philippine Sea. The Philippines will deploy three navy vessels, two FA-50 fighter jets and an A-29B Super Tucano attack aircraft to join a US littoral combat ship and P-8A plane in the activity. No further details were given about what the vessels and aircraft would do. The announcement comes after Marcos warned Sunday that the Chinese military had “started to show interest” in building bases on reefs that were “closer and closer to the Philippine coastline”. China deploys boats to patrol the waterway and has built artificial islands that it has militarised to reinforce its claims to almost the entire South China Sea. China has ignored an international tribunal ruling that its claims have no legal basis. Tensions between Manila and Beijing have flared in recent weeks following several incidents between Philippine and Chinese vessels in the sea. This month, Manila accused the Chinese coast guard of “dangerous harassment” of Philippine boats, including firing a water cannon and blocking vessels on a resupply mission. That came after two collisions between Philippine and Chinese boats in the same area, with the countries trading blame.