The only question here is why civil trawlers but not coast guard or naval patrol, if China wanted to prevent US vessel from continuing its surway in the area? Reminds me 1988 accident when US ships were ramed by Border guards from Soviet waters on Black sea, as well as old joke about Soviet agricultural tractors (Chineese trawlers) capable to wanish the Kingdom of Belgia with rare gunfire (as their numerous flags on masts look like old fashioned combat flags.
