South Korea, US begin military exercises as North issues threats

South Korea and the United States on Monday began joint military exercises, days after North Korea's leader warned his army would turn the sea "into a graveyard of the invaders", DPA reported.

The Ulchi Freedom Guardian exercises would last through August 31 and were designed to strengthen the readiness of US and South Korean forces to defend South Korea, the two militaries' Combined Forces Command said.

About 56,000 South Korean troops and 30,000 US soldiers would participate in the computer-assisted simulation exercises in and near Seoul that were designed to improve commanders' decision-making abilities, it said.

The joint military exercises routinely draw rebukes from Pyongyang, which charges that they are meant to prepare for an invasion of North Korea, but Seoul and Washington insist that they are defensive.

The Combined Forces Command said North Korea was informed of the exercises and the "non-provocative nature of this training."

The exercises began two days after North Korean state media reported that leader Kim Jong Un visited the artillery unit that carried out a 2010 bombardment of a South Korean border island that killed four South Koreans and ratcheted up tensions between the neighbours.

Kim, who came to power after his father's death in December, told the unit on the border island of Mudo never to allow aggression from North Korea's enemies to go unanswered.

If even one shell falls on North Korean territory, the Korean People's Army "should lead the battle to a sacred war for national reunification," Kim was quoted as saying by the Korean Central News Agency.

"He also ordered it to turn the West Sea into a graveyard of the invaders," the report said, referring to the body of water also known as the Yellow Sea.

The November 2010 shelling of the South Korean island of Yeonpyeong was the first attack by North Korea on South Korean soil since the 1950-53 Korean War. Both sides blamed the other for starting the confrontation.

Kim charged South Korea and the US with "threatening peace and stability" with "provocative war drills."

The two Koreas remain technically at war after a ceasefire and not a peace treaty ended the Korean War.