The Philippines released new aerial photographs of China's "massive" construction project to build artificial islands in hotly disputed waters on Monday, warning of their potential impact on regional stability, trade routes and the environment.
The new images came as the Philippines and the United States began their largest joint military exercises in 15 years — the "Balikatan" (shoulder-to-shoulder) war games will involve a total of 11,000 personnel.
The Philippines is just one of China's maritime neighbors with which it is locked in territorial disputes over parts of the South China Sea.
The construction project in the Spratly Islands involves dredging sand from the ocean floor and piling it on existing coral reefs to form large reclaimed land masses. These artificial islands appear to include a runway, shipping docks and at least one multi-story building.
Gen. Gregorio Pio Catapang, chief of state of the Philippine army, told a press conference on Monday that his country had "compelling reasons to raise our voice to tell the whole world the adverse effects of China's aggressiveness."
Catapang said the project would result in "the destruction of 300 acres of coral reef systems," leading to "irreversible and widespread damage to the biodiversity and ecological balance" in the region.
Furthermore, he said, it could disrupt international shipping lanes. "We also believe that China's massive reclamation activities will cause tensions among claimant countries not only because it could deter freedom of navigation but also due to its possible military purposes," he added.
President Barack Obama recently expressed concern that China was using its "sheer size and muscle" to bully other countries in the region.
China's foreign ministry defended its construction project as " justifiable and lawful" and "beyond reproach." Spokesperson Hong Lei told NBC News on Monday that the islands were being built to aid the country in its "maritime search and rescue, disaster prevention and mitigation, marine science and research," and other areas.
He added that the islands were far away from any shipping lanes and had been built "following a high standard of environmental protection."
Satellite photos released by military magazine IHS Jane's Defense Weekly in February showed evidence of China's "methodical, well-planned campaign to create a chain of air and sea-capable fortresses," according to the magazine's Asia-Pacific editor James Hardy.