Investigators said on Thursday that a North Korean torpedo sank a South Korean warship near the disputed Yellow Sea border in March, with the loss of 46 lives.
Here is a brief history of clashes between the two nations since the 1950-1953 Korean War, which ended in an armistice and not a formal peace treaty.
January 21, 1968: North Korean commandos stage a raid on Seoul's presidential Blue House in an attempt to assassinate President Park Chung-Hee. They are stopped just 800 metres away. All 32 are killed or captured in subsequent days.
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August 15, 1974: North Korean agent fires at Park during a speech. He misses but the shot kills the president's wife. Park continues his speech.
October 9, 1983: The North's agents blow up a landmark in Burma just before the visiting South Korean President Chun Hoo-Hwan is set to arrive. Four South Korean cabinet ministers and 16 others are killed.
November 29, 1987: All 115 people on board are killed when a bomb planted by the North's agents explodes on a South Korean airliner.
September 1996: A North Korean submarine lands commandos on the South Korean coast, prompting a huge manhunt. Twenty-four infiltrators are shot dead including 11 by their own hand, one is captured and one unaccounted for.
June 15, 1999: A clash breaks out along the Yellow Sea border, the first naval battle since the Korean War. A North Korean boat with an estimated 20 sailors aboard is sunk.
June 29, 2002: A South Korean ship is sunk and six sailors killed in another Yellow Sea clash, while Seoul is co-hosting the football World Cup. An estimated 13 North Koreans die.
November 10, 2009: Navies of the two sides exchange fire near the Yellow Sea border. Seoul officials say a North Korean patrol boat retreated in flames but its casualties are unknown. No South Koreans are hurt.
March 26, 2010: An unexplained explosion hits the 1,200-tonne South Korean corvette the Cheonan near the disputed border, and breaks it in two. A total of 58 sailors are rescued but 46 die.
May 20, 2010: A report by a multinational investigation team says a North Korean submarine launched a torpedo which sank the ship.
