Perhaps it was the Chinese ship that was to deliver oil to North Korea and they had an accident while maneuvering to make the transfer.
Transferring gasoline at sea seems like a fairly tricky proposition.
I am suspicious. We know that the Iranians and the ChiComms are cheating on the sanctions and delivering fuel to the Norks. I think this was a fuel transfer operation gone wrong.
The question is, did this happen spontaneously, or did this accident have help?