Philippine-US joint naval drill amid tension with China
The Philippines and the US have begun 11 days of joint naval exercises amid growing tensions with Beijing over disputed waters in the South China Sea.
US missile destroyers will join much older Philippine warships for the drills off the south-west Philippines.
In a BBC interview, President Benigno Aquino said he was concerned by China's encroachment into Philippine waters.
Several Asian nations claim parts of the strategically important waters that may also contain oil and gas deposits.
The naval exercises are an annual event and will be an important chance for Manila's badly equipped navy to learn new techniques.
But they come at a strategically important time, not far from the disputed region of the South China Sea in which the Philippines says China has made a series of recent incursions.
On Monday, the US Senate unanimously approved a motion deploring "the use of force by naval and maritime security vessels from China in the South China Sea".
Democratic Senator Jim Webb said South East Asian nations were worried about China's "pattern of intimidation".
As a former US colony, the Philippines still has close ties with America.
The US has already stated its intention to honour a long-standing defence pact made with the Philippines should the need arise.
The exercises will undoubtedly give the Philippines more reassurance of US support should China continue to press its claims on the disputed territory.
Manila says there have been nine separate Chinese incursions into its territorial waters since late February, and President Aquino said he was very concerned about the situation.
He told the BBC that if China did push its claim in some way, it would be "hard to understand how this could conform to international law".
"And if the international community agrees to such a thing, what happens to the rule of law?"
For its part, China has said it will not resort to the use of force to resolve maritime border disputes in the South China Sea.
China's foreign ministry says it condemns any action that would exacerbate the dispute, and urged those involved to "do more that is beneficial to regional peace and stability".