ATLANTA – With US and Chinese warships increasingly playing chicken, and China transforming atolls and outcroppings into militarized artificial islands, the South China Sea presents a striking picture of Sino-American strategic competition. But China’s expansive assertion of offshore sovereignty is not only challenging others’ territorial rights and free navigation of international sea lanes. It also is threatening a central feature of the Southeast Asian ecosystem, and thus the region’s economic future. China has refused to submit its territorial claims to international review, even though six of the ten countries surrounding the South China Sea have claims to various rocks, shoals, reefs, and resources within its 1.4 million square miles. China also has ignored the Permanent Court of Arbitration’s (PCA) 2016 ruling affirming the Philippines’ historic rights to the Spratly Islands and dismissing China’s outsize claim to some 90 percent of the South China Sea (based on