More than 11,500 American and Filipino military personnel have started one of their largest annual exercises for combat readiness amid growing alarm over China's massive land reclamations in disputed South China Sea territories.

Philippine military officials said Monday that the "Balikatan," or shoulder-to-shoulder, maneuvers were not directed at China. But the venue of some of the war games in waters facing the disputed region and a focus on territorial defense appear to link the exercises to the long-simmering conflict.

Shortly before overseeing the start of the military exercises, Philippine military chief Gen. Gregorio Pio Catapang Jr. held a separate news conference to show surveillance photos of Chinese reclamations in eight previously submerged reefs in the disputed Spratly Islands, saying Beijing's actions increase the risk of an accidental confrontation.