North and South Korean border clashes follow years of tension
North and South Korea have exchanged dozens of artillery shells across their tense western sea border, in one of the most serious incidents since the Korean War ended without a ceasefire in 1953.
The incident comes days after North Korea revealed it had a modern uranium enrichment plant - giving rise to fears that it may be trying to develop a nuclear weapon.
Tensions between the two Koreas have remained high since the sinking of a South Korean ship in which 46 sailors died in March.
BBC's Andy Moore reports.