Yeonpyeong island
* Lies 3km (2 miles) from disputed Yellow Sea border and 12km from North Korean coast
* Houses military installations, a permanent Marine detachment and a small civilian population
* Rich fishing grounds in surrounding waters
* Scene of inter-Korean naval clashes in 1999 and 2002
* In the 2002 exchange of fire, 13 Northern sailors and five Southern sailors were killed
North Korea: Timeline 2010
26 March: South Korean warship, Cheonan, sinks, killing 46 sailors
20 May: Panel says a North Korean torpedo sank the ship; Pyongyang denies involvement
July-September: South Korea and US hold military exercises; US places more sanctions on Pyongyang
29 September: North holds rare party congress seen as part of father-to-son succession move
29 October: Troops from North and South Korea exchange fire across the land border
12 November: North Korea shows US scientist new - undeclared - uranium enrichment facility
About 28,500 U.S. troops are stationed in South Korea, a legacy of the three-year-long war.
North Korean artillery hits South Korean island.