By militarizing the South China Sea, China is seeking to establish a de facto Air Defense Identification Zone like the one that it formally – and unilaterally – declared in 2013 in the East China Sea, where it claims islands that it does not control. China knows that, under international law, its claim to sovereignty over virtually all of the resource-endowed South China Sea, based on an “historic right,” is weak; that is why it has opposed international adjudication.