Barack Obama heightened rising tension with China today ahead of a regional summit today in Manila.
The US President reaffirmed his commitment to the Philippines' security and freedom of navigation in Asia in direct challenge to Beijing's claims to disputed islands in the South China Sea. The comments puts the territorial dispute firmly on the agenda for the Asia Pacific Economic Cooperation (APEC) summit.
"My visit here underscored our shared commitment to the security of the waters of this region and to freedom of navigation," said Obama.
Although he did not mention China, the symbolism of his comments aboard the Philippines' main warship was evident. The ageing vessel is a key part of the Philippine Navy's operation around the Spratly Islands in the South China Sea. Both China and the Philippines claim the islands as their own.
Obama's comments came shortly after the Chinese Vice Foreign Minister Liu Zhenmin said China was the real victim of the dispute.
"The Chinese government has the right and the ability to recover the islands and reefs illegally occupied by neighbouring countries," said Liu. "But we haven't done this. We have maintained great restraint with the aim to preserve peace and stability in the South China Sea."
Beijing has overlapping claims with Vietnam, the Philippines, Malaysia, Taiwan and Brunei in the South China Sea, through which $5 trillion in ship-borne trade passes every year.
A week before the summit, US B-52 strategic bombers flew near Chinese artificial islands, signaling Washington's determination to challenge Beijing over the disputed sea.
Chinese President Xi Jinping, who recently enjoyed a state visit to Britain, also arrived in Manila today for the APEC summit, but did not make any public comments.
Obama and Xi will be among about 20 heads of state and government attending the main APEC meeting on Wednesday and a leaders retreat on Thursday. The Philippines has said it will not bring up the South China Sea dispute to avoid embarrassing Xi, but it could not prevent others from doing so.
The APEC meet is the first of two regional summits that were supposed to bolster trade and security ties but have been clouded by last week's coordinated attacks on Paris.
For Obama, the latest flurry of summits illustrates how his effort to "rebalance" US policy toward Asia-Pacific countries has consistently run into the geopolitical reality that the persistently volatile Middle East cannot be ignored.
Obama will likely discuss the friction over the South China Sea and military relations when he meets Philippine President Benigno Aquino on the sidelines of the summit on Wednesday.
Aquino and Japan's Prime Minister Shinzo Abe are also expected to agree on a deal paving the way for Tokyo to supply Manila with used military equipment, possibly including aircraft that could be deployed to patrol the South China Sea, sources said.
Manila and Hanoi are also due to sign a strategic partnership deal governing how their navies will work together.
Additional reporting by Reuters