These boats should be blown out of the water with their crew.
I'm not totally against the idea.
However, I say "Remove the crew from the boat (and imprison them) and as long as it's not in an area of frequent shipping (deep enough water), sink it with the cargo on board."
Film the seizure on tape as well as the naval gunfire that sinks the ship. Make sure the video gets sent to youtube.com, the MSM, etc.