On Tuesday, Aug 3 North Korean command responsible for the North"s western maritime border made the threat of a strong physical counterattack.
South Korea is planning the naval exercises in reaction to the sinking of a South Korean warship, ROKS Cheonan, in Mar 26 in which 46 sailors died.
An international team of investigators in May 2010 found that a North Korean submarine fired a torpedo that sank Cheonan. The US and South Korea called the sinking a violation of the armistice that ended the fighting in 1953.
South Korea and the United States held joint naval manoeuvres on last week of Jul 2010.