The United States and the Philippines launched annual joint naval war games on Monday, days after the latest diplomatic row between Manila and Beijing over the disputed South China Sea.

More than a thousand sailors from the two allies are taking part in the annual "Samasama" (Tagalog for Together) anti-submarine, surface and electronic warfare drills off Manila and the south of Luzon, the main island of the Philippines.

China's assertiveness in the South China Sea, which Beijing claims almost in its entirety despite a 2016 international ruling that it has no legal basis, have become a growing concern for Washington and its regional allies.

US Pacific Command chief Vice Admiral Karl Thomas told sailors at an opening ceremony in Manila that the rights of all nations to ensure national sovereignty were "under attack every day on the high seas".

The "rules-based international order" that guaranteed regional peace for decades has been "ripped at and tagged at and tested to benefit not all nations but one nation," he said, without mentioning China specifically.

"There's no better way to ensure sovereignty and security than to sail and to operate together," Thomas said.

Asked at a news conference to whom he was referring, Thomas said it was important to maintain the right to sail through the area "free from worries about being attacked" or "intimidated".

Beijing has deployed patrol boats in recent weeks that Manila says harass Philippine coast guard vessels and Filipino fishermen in what it refers to as the West Philippine Sea.

Philippine President Ferdinand Marcos ordered a special operation last month in which coast guard personnel cut a rope tethering a floating barrier at the Chinese-controlled Scarborough Shoal.

Manila said the barrier had prevented Filipino fishermen from entering the fish-rich ring of reefs, which China seized in 2012.

Beijing responded by warning Manila "not to provoke or stir up trouble" and restated its sovereignty and maritime rights to what it calls Huangyan island.

Philippine Navy chief Vice Admiral Toribio Adaci said the Samasama exercise "equips us to face an array of threats together".

US Navy officials said the guided missile destroyer USS Dewey would take part in the exercises over the next 12 days, along with a dry cargo ammunition ship and P-8 Poseidon maritime surveillance aircraft.

A Philippine Navy guided missile frigate would also participate, along with a Japanese Maritime Self Defence Force destroyer and the Royal Canadian Navy frigate HMCS Vancouver.

Britain, Japan, Canada, France, and Australia are also sending personnel to tabletop exercises as part of the drills, while New Zealand and Indonesia are sending observers.