Tensions as S Korea and US set for military exercises
25 November 2010 Last updated at 11:27 GMT
South Korea is to strengthen its military force on five islands close to North Korea, amid tensions over a clash that left four people dead.
North Korean shelling of a South Korean island on Tuesday killed two civilians and two marines, and prompted an increase in regional tension.
The BBC's Chris Hogg says North Korea is threatening more attacks with any "further provocation" as joint military exercises between South Korea the US are plannned for Sunday.