Making waves in South China Sea?

A blockade in the South China Sea? That's what the darling of the Filipino media Ray Powell says in a tweet about what China will do in Huangyan Island in the coming days. He is a former U.S. air force serviceman who now heads the Sealight Maritime Transparency Project, an organization that overtly counters China. He warned that China will blockade Filipino vessels carrying activists, foreign observers, journalists, and fishing crew to what is known in English as Scarborogh Shoal, a disputed area. What exactly is Ray Powell up to? Who's behind him?