That was footage of an artillery bombardment exacted by the North Koreans on the South Korean island of Yeonpyeondo. Two South Korean soldiers were killed in the barrage. The surprise attack has received condemnation from the United States, Japan, and Russia while South Korea has vowed to attack a North Korean missile base at the sign of any further provocation.
All in all, this is not a happy state of affairs and I hope that there isn’t further escalation. It would also be nice to know what is going on in North Korea so as to trigger such behavior.