This photo released by South Korean Defense Ministry on June 10, 2016 shows South Korean patrol boats forcing Chinese fishing boats from disputed waters.(Photo by AFP)
This is one of several reports I have seen. A 4.5 ton South Korean “speed boat” (probably around 30 foot or 8 to 10 meter) has been rammed and sunk by a Chinese fishing vessel believed to have been over 100 tons. There were no casualties.
Reports are somewhat confusing, but, the way I interpret the reports, there was a large fleet of Chinese vessels fishing illegally in South Korean waters. A boarding party of eight had boarded one of the fishing vessels leaving one man still in the boat. A second Chinese fishing vessel rammed the boat as it lay alongside the fishing vessel probably crushing it. The one man aboard was recovered safely.
It is not clear to me how the boarding party got off the first fishing vessel or why the vessel was not detained.
A diplomatic protest has been filed with the Chinese.
Thanks to Luke for bringing this to my attention.
Chuck Hill's CG Blog 
Sticky situation. What can the South Korean’s actually do to stop this? Do they only approach and board when protected by larger vessels in close proximity? How many of those have they got? And how are these vessels to protect the RHIBs without simply getting in the way and allowing themselves to be rammed, instead? If they start shooting up Chinese fishing boats they’ll have a lot more than a diplomatic protest coming back at them!
They are going to have to seize and destroy some fishing boats like Indonesia does.
S.Korean CG has a very large number of large cutters. Can’t let boats that do this kind of crap get away.
It is their EEZ, they can chase the Chinese out of it, just like we chased the Russians out of ours. Of course the Chinese will not agree since they think they own everything, but you have to standup for your rights.
Sounds to me like a ROE problem. All conjecture, but follow my line of thinking for a moment:
So. Korea has been confronting these fishing fleet intrusions more and more.
Chinese fisherman have become passively to actively resistant, such as refusing to yield to a boarding, or locking themselves in a compartment.
So. Korea responds by deploying “non-lethal” (incorrect terminology, should be “less lethal”) means, such as the flashbangs, inadvertently killing three fisherman.
Chinese fisherman respond with: “Screw you; we’re coming back, in a group, and will actively resist, since you’re killing us…”
Simultaneously, So. Korean CG leaders (and probably higher officials) say, “oh, crap! Didn’t mean to kill them; we better back off. Change the ROE so we’re kinder/gentler; don’t react to provocation.”
So, here come the pissed off and aggressive Chinese fishermen clashing with the passive/hamstrung So. Korean CG, and you get this situation…
The So. Korean CG had larger vessels on scene. (Presumably where the boat was launched from.). Yet, they did not follow up by, first, guarding their boarding party better, and second, by prosecuting a chase, seizure, and arrest of the ramming boat. I still have a bunch of questions (like why didn’t the boarding party boat move?), but it looks like bad ROE to me…
Your sequence of events sounds plausible. Of course from the Korean point of view, the Chinese F?Vs should not be there at all. The Chinese have been told all their lives that the waters are theirs, and they have a profit motive, so they want to believe it.
Yes, plus, with their own (Chinese EEZ) fishing grounds becoming depleted, and their profit motive, the Chinese fisherman must push into So. Korean waters. With their own fishing grounds depleted, it may not even be “profit” insomuch as the fishermen’s families would starve with no fish to sell…
Another of my unanswered questions is: Does the Chinese government encourage the intrusion or merely condone it and potentially use the results for the government’s motives after the fact?
S. Korea has told China that it will use deadly force in the future. http://navaltoday.com/2016/10/12/south-korea-warns-it-will-shoot-at-chinese-vessels-fishing-illegally/?uid=171