Taiwanese coast guard commander Lin Chie-ming is on the frontline of a new type of warfare that China is waging against Taiwan. China’s weapon? Sand.On a chilly morning in late January, Lin, clad in an orange uniform, stood on the rolling deck of his boat as it patrolled in choppy waters off the Taiwan-run Matsu Islands. A few kilometers away, the Chinese coast was faintly visible from Lin’s boat.