There is some fighting happening between North and South Korea over the island of Yeonpyeong, home to a South Korean naval base and located very near the northern limit of South Korea's territory.
Fighting has happened recently in this area, back in 1999 and again in 2002.
I've scratched out a little backgrounder on this since no one else has touched it ...
Here are North Korea, South Korea, Japan, and China in context.
The island in question is Yeonpyeong, which is the one just beneath the tip of the black line that defines the north/south line.
Wikipedia indicates this one is part of the Incheon Islands, with Yeonpyong depicted as #3 here.
The North Korean navy consists of many small boats and a variety of older submarine designs. They can be a real nuisance to surface ships, particularly through mine laying operations, and they have credible amphibious capability specifically crafted to trouble the south.
The South Korean Navy is larger, with about 60,000 personnel as opposed to the north's 46,000. There are two dozen destroyer sized surface vessels and many smaller ships described as corvettes. The smaller of these fast attack craft are roughly the size of John F. Kennedy's PT boat, the larger ones are similar to our Freedom class Littoral Combat Ships.
The First Battle of Yeonpyeong was in 1999 and the Second Battle of Yeonpyeong was in 2002. Just over a year ago the Battle of Daecheong occurred near the island by the same name, much further west and a bit north of Yeonpyeong.
The situation today is a little different. Instead of just small boats this involves a shore bombardment on South Korean territory. Instead of just Navy personnel now there is talk on Twitter that civilians have been wounded and homes are burning.
This al Jazeera article shows the scope of the damage - massive smoke plumes are rising from multiple locations on the island.
China made the following statement of disapproval per the al Jazeera piece:
China expressed concern over Tuesday's exchange of fire and urged the two sides to work toward peace and stability on the Korean peninsula.
"We have taken note of the relevant report and we express concern over the situation," Hong Lei, a foreign ministry spokesman, told reporters.
"We hope the relevant parties do more to contribute to peace and stability on the Korean peninsula."
Some Korean Peninsula watchers I was in contact with say it's unusual to see shore targets being involved in such an exchange, but this is otherwise a relatively normal sort of tension between the two countries. Chinese disapproval of this move should quickly put a damper on the action.
I wouldn't normally use a story from the Torygraph (Brit Fox News clone) but in this case it's good stuff - Russia also disapproves of North Korea's behavior.