In the artillery firing, two soldier were killed and four marine solider were seriously injured. The military was trying to evacuate civilians on the island near the border. Several civilians were reported to have suffered injuries.

Foreign press quickly reported the attack as a major news, producing a flurry of interpretations about the motive of North Korea. Reuters quoted an expert as saying that the attack is "unbelievable."

The firing came as the South was carrying out a live-fire exercise in waters off the Bangnyeong Island and the Yeonpyeong Island as part of the annual nine-day Hoguk Exercise, aimed at enhancing interoperability and defense capabilities against North Korea.

Regarding the Hoguk Exercise, the North sent a faxed message to the South in the morning, saying it would not “just sit back while the South is carrying out the live-fire exercise, according to JCS officials.

“Our military has begun operating the crisis management system and strengthened a readiness posture in all military branches. We are fully and firmly prepared to respond to additional North Korean provocations,” Lee said.

The JSC called on the North to immediately stop acts that ratchet up military tension on the peninsula and inter-Korean confrontations. “We will strongly respond to any further provocations from the North,” the spokesman said.

The presidential office of Cheong Wa Dae said it was looking into whether the North fired the artillery in reaction to the South Korean navy’s “Hoguk Exercise” near the island.

“North Korea wired a complaint this morning asking whether (the exercise) was an attack against the North,” President Lee Myung-bak’s spokesperson Kim Hee-jung said during a press briefing.

Lee held emergency meetings of his top aides and security related ministers in the afternoon.

The volley of artillery came as tensions have run high between the two Koreas following the March 26 sinking of the corvette Cheonan, which Seoul holds Pyongyang responsible for.

The Seoul-led multinational investigation team concluded in May that a North Korean midget submarine torpedoed the 1,200-ton corvette, killing 46 sailors. Pyongyang has persistently denied its involvement.

In August, the North fired some 130 coastal artillery shells into waters near the western inter-Korean maritime border. Some 10 coastal artillery shells landed in waters about 1-2 kilometers south of the Northern Limit Line off Bangnyeong Island.

The volley of the artillery fire came after the South Korean military finished its five-day maritime maneuvers in the West Sea, which were designed to enhance its defense capabilities against North Korean provocations.

The artillery firing came as a surprise as North Korea experts here largely anticipated that the communist state would seek to improve ties with its southern neighbor as it has been striving to solidify its second hereditary power succession.

The North has recently made it public that its leader Kim Jong-il’s youngest son Jung-un is being groomed to succeed his ailing father. Jung-un has recently been made a four-star general and appointed as vice chairman of the ruling Worker’s Party’s Central Military Commission.

By Song Sang-ho (sshluck@heraldcorp.com)