He will then head to Singapore for the annual Shangri-La defense forum, where he will meet with a number of regional defense leaders and experts.
"The Philippine government continuously monitors the actions of the various claimants in the SCS/WPS (South China Sea/West Philippine Sea)".
China's claim over the South China Sea is different from its neighbors' interpretations.
China earlier this month landed bomber aircraft capable of carrying nuclear weapons on its main base at Woody Island in the Paracels.
It was the primary time multiple U.S. vessel had been used within the workouts, in line with specialists, a part of a latest escalation in U.S. opposition to China's motion within the area.
He noted that Chinese President Xi Jinping promised at the White House in 2015 that China would not be militarizing areas near the Spratly Islands, but the United States saw last month that it had done exactly that, moving in weaponry that was not there before. "We have seen in the last month they've done exactly that, moving weaponry in that was never there before", Mattis said.
Reuters first reported that two U.S. Navy warships sailed near South China Sea islands claimed by China on Sunday, even as President Donald Trump seeks Chinese cooperation on North Korea. The FONOP angered China, which considers the body of water as part of its domain.
As Mattis states, there's "only one country" that seems to be resentful of, and emphasize its opposition to, the maintenance of free and open trade lanes.
In a briefing with the House special committee on the West Philippine Sea, Cayetano said the Philippines has been filing diplomatic protests for two years already, but they chose not to announce these regularly.More news: Zidane stuns Real Madrid by stepping down as coach
He contrasted the U.S. Navy's FONOPs with opaque Chinese behavior.
"They're freedom of navigation operations".
China said it has dispatched warships to identify and warn off the United States vessels.
"We're going out of our way to cooperate with the Pacific nations".
"The Philippine government has not been remiss in undertaking diplomatic actions against any nation", Esperon said.
Cayetano further elaborated that among the territorial issues discussed, with China, were construction activities at a disputed shoal and the unilateral extraction of oil and gas in the region.
The Chinese navy helicopter "was so close that seawater splash entered the rubber boat", said Alejano, who asked the government to disclose more details of such incidents to the public.
Amid accusations that the Philippines was not taking advantage of an arbitral ruling that upheld Philippine sovereign rights over disputed territories in the West Philippine Sea, Esperon said, "This Administration does not and will not abandon the ruling of the Permanent Court of Arbitration on the South China Sea disputes".
The US secretary of defense is expected to preside over the change of guard in the US Pacific Command.