In the South China Sea, the Spratly Islands are just of several districts that China has militarized. These are the Paracels, Pratas, and the Scarborough shoals that are in China's grip.
Beijing sees these parts of SCS as China's holdings and is making claims that are not substantiated by the Law of the Sea Convention or the Law of the Sea treaty (UNCLOS), using this to claim parts of the ocean and outcroppings as proof of its ownership that has been refuted by international courts.
China hoodwinks President Obama in 2015
When Xi Jinping visited the White House and talked to then-President Barack Obama about the Spratlys and similar areas, he asked if China will militarize the Spratlys, Xi said that Beijing has no intention to.
During this time, China was already building on Nansha (the Chinese name for Spratly) when it was opened up by Obama. Now, five years later, China has several installations that include an airfield. Also, the Island is fortified with missiles batteries.
There's a proof that Beijing did not honor its pledge, as result in 2020 there are two carrier strike groups in the SCS, cited The Diplomat. The US Navy has a larger military presence to counter the communist's attempt for the Dominion of the SCS.
Why is the Spratlys important for China to hold onto and maintain in the South China Sea?
The US Navy has been conducting freedom of navigation operations (FONOPs) that emphasize that the Chinese cannot monopolize the sea lanes. Nansha is strategically right in the middle of the SCS, as China develops it more, there will be problems for ships plying this part of the world.
Facilities are already established and Nansha is used to send PLA Navy to terrorize non-military ships from passing. Legally, it is only 12 nautical miles from an island, but the PLA Navy insists that a bigger part is the sovereignty of China.
If China controls this part of the South China Seas in the Spratlys, it brings trouble to the establishment of air defense identification zone (ADIZ) in the South China Sea.
There is an ADIZ in the East China Sea that is no worth it. ADIZ in the Nansha gives Chinese control of the surrounding airspace. The establishment of airfields and hangers signifies an intention to militarize the airspaces illegally.
Once the ADIZ is developed, there will be a threat to other claimants of the district. PLA Airforce can run missions in support of its domination goal. A fully established ADIZ will even be a danger to the US Navy.
Natural resources in the South China Sea will be exploited for Chinese gain.
The Nansha is just a chess piece for Beijing to dominate the SCS, with no intension to leave. Resources in the area are fishing stock and a bit farther is oil with other exotic energy sources.
Communists want to consolidate resources as their own, even stealing from the Philippines, Vietnam, and Malaysia is not beyond them.
America declares the surrounding areas are not Beijing's, which chaffs Xi Jinping. Tension is souring as China says it owns the Spratlys in the South China Sea.