South Korea said on Thursday it would increase troops on islands near North Korea with Pyongyang warning it would follow its bombardment earlier in the week with more attacks if its wealthy neighbor tried any "provocations".
The sudden spike in tension in the world's fastest growing economic region is putting mounting pressure on China to rein in its prickly ally. South Korean media reports said Tuesday's artillery attack was likely personally ordered by reclusive North Korean leader Kim Jong-il.
"(North Korea) will wage second and even third rounds of attacks without any hesitation, if warmongers in South Korea make reckless military provocations again," the North's KCNA news agency, using typically bellicose language, quoted a statement from the military as saying.
"The U.S. cannot evade the blame for the recent shelling," it added. "If the U.S. truly desires detente on the Korean peninsula, it should not thoughtlessly shelter the South Korean puppet forces but strictly control them so that they may not commit any more adventurous military provocations."
The United States and South Korea are to hold joint military exercises next week, with the aircraft carrier USS George Washington participating, although KCNA made no mention of that.
"Over telephone talks with Secretary (of State) Hillary Clinton, we agreed that through the drill, we will be able to ...send a clear message to the North in relation to the recent situation," a South Korean Foreign Ministry spokesman said.
North Korean leader Kim and his son and designated heir, Jong-un, visited the Yellow Sea coastal artillery base from where shells were fired at a South Korean island near the disputed maritime boundary just hours before the attack, newspapers in Seoul said.
South Korea's military was "focusing on the possibility of Kim Jong-il and his son approving the shelling of Yeonpyeong", the Chosun Ilbo quoted an unnamed member of the National Assembly's Defence Committee as saying.
The government declined comment but, if correct, would rule out one theory that the North's bombardment of Yeonpyeong, just south of the disputed border, might have been the decision of a rogue military commander.
At least four people, including two civilians, were killed and dozens of houses destroyed on the island in the heaviest attack by the North since the Korean War ended in 1953.
It marked the first civilian deaths in an assault since the bombing of a South Korean airliner in 1987. North Korea said the shelling was in self-defense after Seoul fired shells into its waters.
South Korean President Lee Myung-bak convened an emergency meeting early on Thursday to look at how to contain the economic impact from the attack and additional security measures.
The military presence on islands in the Yellow Sea near the disputed border will be boosted and an earlier plan to scale down marine troops stationed there will be cancelled, a presidential Blue House official said later.
South Korea also said it would pursue constructive engagement with China to use its influence over Pyongyang.
That plan looked to have suffered a setback with a later announcement that Chinese Foreign Minister Yang Jiechi had delayed a plan to visit Seoul this week. No reason was given.
Many analysts expect the plan to send the nuclear-powered aircraft carrier to the joint exercises will enrage the North and unsettle China.
Beijing has said previously that it sees any joint U.S.-South Korea exercises in the waters between the Korean peninsula and China as a threat to its security and to regional stability.
China has long propped up the Pyongyang leadership, worried that a collapse of the North could bring instability to its own borders. Beijing is also wary of a unified Korea that would be dominated by the United States, the key ally of the South.
"If China does not put public pressure on North Korea, provocations by North Korea will continue," Seoul's Chosun Ilbo newspaper said. "If the Korean peninsula is in flames, Chinese prosperity will shake from the bottom."
The deaths of civilians have added to anger in the South.
"Let me say a word about those bastards at the Blue House who advised the president to say the situation should be managed to avoid a full-blown war," the Korea Joongang Daily quoted ruling party Rep Hong Sa-duk as saying.
"They must all be fired for advising the president to have such a weak response."
While the rhetoric continues, global markets have moved on to other issues after Tuesday's attack. The stock market opened up in Seoul on Thursday and looked likely to head back to pre-attack levels. However, the won currency remained under pressure due to lingering caution.
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