US PRESIDENT Barack Obama ended his two-day state visit to the Philippines reaffirming Washington's commitment to defend its South-east Asian ally, saying it is "ironclad".
"The United States will keep that commitment because allies never stand alone," he told about 500 Filipino and American servicemen at the Philippine Army headquarters just outside Manila.
Mr Obama said that commitment stems from a "mutual defence treaty" the Philippines and the US signed over 60 years ago.
"This treaty means our two nations pledge - and I'm quoting - our 'common determination to defend themselves against external armed attacks, so that no potential aggressor can be under the illusion that either of them stands alone'," he said.
Mr Obama later laid a wreath at the Manila American Cemetery, where the largest number of American soldiers killed in World War II outside the US are interred.
In his speech yesterday, he voiced concern over an escalating row between Manila and Beijing over dozens of uninhabited rocky outcrops, atolls and reefs in the resource-rich South China Sea.
"We believe that nations and peoples have the right to live in security and peace and have their sovereignty and territorial integrity respected," he said. "We believe that international law must be upheld, that freedom of navigation must be preserved and commerce must not be impeded."
Throughout his Asian swing, Mr Obama repeatedly asserted that the key to prosperity in Asia is in China playing by the rules, rather than bending them to suit its interests.
"It is inevitable that China is going to be a dominant power in this region just by its sheer size," he said on Monday.
"The question is just whether other countries in the region are also able to succeed and prosper on their own terms and attend to the various interests and needs that they and their people have as well. That's what we support."
Beijing's growing assertiveness in pushing its claims over 90 per cent of the South China Sea has set it against states with rival claims: the Philippines, Malaysia, Vietnam and Brunei.
Manila filed a case with an international arbitration court last month contesting China's claims. But Beijing says the case lacks basis and that it will not abide by whatever ruling comes out of it.
On Monday, the Philippines and the US signed a 10-year defence pact in one of the clearest signs of renewed American engagement in the region.
Mr Obama assured Beijing that the pact was not meant to "contain" or "counter" China.
But in an editorial yesterday, the China Daily derided that assurance as "hollow" rhetoric. "Ganging up with its troublemaking allies, the US is presenting itself as a security threat to China," it said.
Mr Obama left for Washington yesterday, ending a four-nation tour beginning last Wednesday that also took him to Japan, South Korea and Malaysia.