China claims an island in the South China Sea. Satellite images show Beijing’s growing power-hungry struggle in the region.

This has been a yearslong power struggle between China and many countries, including the Philippines, Vietnam, and Taiwan, for control of dozens of disputed reefs, islands, and sandbars in the South China Sea.

Up to $5 trillion in goods are shipped across the sea a year.

The problem is that China’s claims of sovereignty over these artificial landmarks are unlawful, according to the United Nations Convention on the Law of the Sea (UNCLOS).

Both the Philippines and China, as well as Taiwan and Vietnam, claim the reef as their own. However, a UN tribunal ruled in 2016 that no territory can claim it.

That didn’t stop China from building an impressive military base there.

In recent months, multiple Chinese vessels in the South China Sea have threatened to collide with Philippine ships in a region called Scarborough Shoal, north of Mischief Reef.

Also in Scarborough Shoal, a Chinese Navy helicopter flew dangerously close, within 10 feet, of a Philippine patrol plane in February, AP reported.

Sandy Cay isn’t an underwater reef. The islands remain above ground at high tide, which grants them legal status as a “rock” (or land surrounded by water) under UNCLOS.

This means that whoever is the rightful sovereign can also claim 12 nautical miles of the waters around it, Poling said.

Both China and the Philippines claim sovereignty over Sandy Cay, but neither has it legally.

The photo-off on Sandy Cay is more of a stunt than a threat, Poling said.

However, if matters escalate in the South China Sea, particularly in Scarborough Shoal, the US has a mutual defense treaty with the Philippines, agreeing to come to its aid in the event of an armed attack. It hasn’t reached that point and will likely deescalate before that, Poling said.

“It is illegally occupied unless China can claim the territorial sea in which it sits,” Poling said.

While China, Vietnam, and the Philippines all lay claim to the reef, China’s military presence gives it effective control.

However, China is no longer the only nation building artificial islands in the South China Sea.

At 118 acres, though, it’s nowhere near the scale of some of China’s developments on Mischief, Subi, and Fiery Cross Reefs.

“The Philippines, Vietnam, even Malaysia and Indonesia have done a pretty good job holding firm,” Poling said, adding that, “I think China just believes it can outlast the other claimants, and that if it keeps up this persistent cycle of pressure, eventually they’ll all crack.”