The Department of Foreign Affairs said "failure to challenge false claims of sovereignty would undermine this order and lead China to the false conclusion that its claims are accepted as a fait accompli."
"It is important for the international community to safeguard freedom of navigation and overflight in the South China Sea," it said. "This is of paramount concern to all countries."
Former Philippine national security adviser Roilo Golez called on President Benigno Aquino III to convene a meeting of top security officials to discuss what the country should do in case Chinese and U.S. forces get entangled in an armed confrontation.
"This is a situation where a world superpower and an emerging one are about to go on a collision course," Golez said. "We should not be caught by surprise."