Thousands of US and Filipino troops began annual military exercises on Friday which the Philippines said were vital to building its defence capabilities against the rising threat of China.
Philippine Foreign Secretary Albert del Rosario used the launch of the 12-day Balikatan manoeuvres to accuse China of destabilising Asia with aggressive and illegal actions in the South China Sea.
"For our region excessive and exaggerated maritime and territorial claims have not only created uncertainty but have undermined the rule of law," del Rosario said in a speech at the nation's military headquarters in Manila.
"Regional peace and stability have been placed at serious risk."
Del Rosario later told reporters he was referring specifically to China.
China claims most of the South China Sea, including waters and tiny rock outcrops near the coasts of smaller neighbours such as the Philippines.
Tensions have escalated in recent years as China has sought to stamp its authority over the region.
The Philippines has accused China of occupying a shoal close to its main island, and appealed to the United Nations to rule on the validity of Chinese claims to the resource-rich sea.
The Philippines has sought closer diplomatic and military ties with the United States, its former colonial ruler, amid the rising tensions.
The two countries share a 61-year-old mutual defence pact, which requires that the United States comes to the aid of the Philippines if it is attacked.
Del Rosario said the Balikatan (shoulder-to-shoulder) exercises were very important.
"For my country we need to secure our borders and protect our territorial integrity more vigorously than we have before," he said.
"Balikatan, with its complicated and complete set of exercises, is an important contribution in not only preparing both our armed forces to work together but also in building my country's own capacity to defend itself."
The manoeuvres involve more than 8,000 US and Filipino troops, 30 military aircraft including a dozen US F/A-18 Hornets and three naval vessels, the two countries said.
The two sides will allow the media to cover some of the exercises next week, including combat drills and simulated rescue work for natural disasters.