http://www.bbc.com/news/world-asia-40314128
This link shows a very erratic course taken by the freighter. Looks like they may have made an initial course deviation that took them towards an island, reversed course to find the channel, then veered to get back on their originally intended course.
I suspect that if the US ship was stopped, the decision to do so while broadside to an erratically approaching craft was a poor one and will likely cost the commander his career.