South Korean forces are on top combat alert following one of the most serious border incidents in years with the forces of communist North Korea.
Northern heavy artillery pounded an island close to the maritime border between the two states, setting dozens of buildings on fire, forcing the evacuation of the local civilian population and killing two South Korean marines.
South Korean President Lee Myung-bak initially said he was trying to prevent a broader conflict breaking out.
But speaking after an emergency meeting of the government in an underground war room, Lee said that his country’s army had a “duty” to retaliate.
"A hundred statements or meetings wouldn't work," Lee said. "I think it's the duty of the army to respond with action. Especially, we can never tolerate unconditional attacks against civilians."
The hour-long attack killed two South Korean marines, injured more than a dozen other people, and caused the evacuation of civilians from Yeonpyeong Island. Dozens of buildings were burning, with dense black smoke rising above the island.
F-16 fighter jets immediately scrambled to guard against any intrusion of air space by Northern aircraft.
North Korea apparently began shelling when South Korea held a routine training exercise close to the disputed Yellow Sea maritime border. The South returned fire, and the incident quickly escalated.
North Korea's deputy UN ambassador, Pak Tok-hun, said that his country had acted in self-defense.
The western maritime boundary between the two Koreas has been the scene of numerous clashes in the past.
In March, a South Korean warship sank near the border, causing the deaths of 46 sailors. The South blamed a North Korean torpedo strike, while the North denied responsibility.
Condemnation And Calls For Calm
The United States, a key ally of South Korea that maintains some 28,000 troops there, swiftly condemned the attack.
A White House statement called on Pyongyang to “halt its belligerent action and to fully abide by the terms of the Armistice Agreement,” a reference to the 1953 pact that ended the Korean War. South Korean officials have also called the strike a breach of the armistice.
U.S. President Barack Obama was expected to call the South Korean president later in the day, as a U.S. State Department spokesman said Washington and its partners would carry out a "measured and unified response."
Speaking to reporters in Beijing, the U.S. envoy on North Korea, Stephen Bosworth, said that both he and Chinese officials agreed on the need to defuse the rising tensions.
"The subject did, of course, come out with my meetings with the Chinese Ministry of Foreign Affairs, and I think we both share a view that such conflict is very undesirable, and I expressed to them the desire that restraint be exercised on all sides and I think we agree on that," Bosworth said.
German-based international affairs analyst Sebastian Harnisch told RFE/RL that he believes China is working behind the scenes to dissuade the North Koreans from more aggressive behavior. He said Beijing has no interest in seeing clashes between the Koreas or with the United States:
"China is the most important power broker when it comes to reining in North Korea at this specific point in time," Harnisch said, "and I'm sure the Chinese government has sought to intervene with Pyongyang to prevent any further escalation."
In Moscow, Russian Foreign Minister Sergei Lavrov added his voiced to the international response, warning that escalations in the North-South conflict represent a "colossal danger."
"I think what happened has to be condemned," Lavrov said. "Those who initiated this and started shelling the South Korean island in the area of the DMZ [demilitarized zone] of course bear a huge responsibility. It is necessary immediately to stop any exchange of fire."
Japanese Prime Minister Naoto Kan said in Tokyo that he had told his government and military to be ready for all eventualities.
"Firstly, I asked our people to put an all-out effort in gathering information on this incident," Kan said. "And secondly, I asked that they prepare for all eventualities. Those are the two orders I just gave out."
One Week, Two Shocks
The events occurred just days after North Korea revealed the existence of a new uranium-enrichment facility. That facility was visited by a prominent U.S. scientist, who described what he saw as "stunning."
Highly enriched uranium can be used to make nuclear weapons.
Bosworth, the U.S. envoy on North Korea, said that there can be no resumption of stalled six-party talks on the North Korean nuclear program while Pyongyang continues to expand enrichment. Chinese officials have backed a return to talks.
So why has the North hit the world with two shocks in the same week?
Analysts speculate that a likely reason for the dual shocks out of North Korea is that the leadership in Pyongyang is seeking to put pressure on Washington in particular to return to the stalled talks or to make other concessions.
Analyst Harnisch said it could also point to a power struggle in the North Korean leadership, as ailing leader Kim Jong Il has just anointed his young and untested son to be his successor.
based on agency and RFE/RL reporting