Tensions are soaring, but Southeast Asian nations are struggling to push back on Beijing’s contested claims and tap the energy resources their growing economies need.

The Philippines is strengthening its relationship with its oldest treaty ally, the United States. The two nations share a complex, close relationship dating to the late 1800s.

The vast energy riches of the South China Sea have long been eyed by the Philippines and Vietnam as a way to reduce their reliance on imported gas and oil. But an armada of Chinese fishing boats and coast guard vessels— including “The Monster”—are blocking their way.