South Korea begins naval drills
South Korea has begun naval drills off its west coast to strengthen its ability to counter any North Korean provocation despite Pyongyang's latest threat to retaliate over the war games.
The drills, which follow joint military exercises with the US last month off the east coast, will include exercises in areas near the disputed western sea border with North Korea.
Both sets of manoeuvres came in response to the sinking of a South Korean warship blamed on North Korea. Forty-six South Korean sailors were killed. South Korea said the drills were to warn the North that further provocations will not be tolerated.
A five-nation team of investigators concluded in May that a North Korean torpedo sank the Cheonan warship in late March near the Koreas' western maritime border.
North Korea, which denies any involvement in the sinking, warned it will "counter the reckless naval firing projected by the group of traitors with strong physical retaliation".
The North had also threatened to respond to the military exercises with "nuclear deterrence" but South Korean military officials said there has been no sign of unusual North Korean military activity.
North Korea routinely issues such threats, especially when the South holds joint military drills with the US. Pyongyang sees the exercises as a rehearsal for an invasion.
The western maritime boundary has long been a flash point between the two Koreas because the North does not recognise the border unilaterally drawn by the United Nations at the close of the 1950-53 Korean War.
The Korean peninsula remains in a technical state of war because the Korean War ended in a truce, not a peace treaty.
South Korea was closely monitoring North Korea's military but spotted no unusual activity, South Korea's Joint Chiefs of Staff said.