WASHINGTON — North Korea's decision Tuesday to sever all ties with South Korea and threaten military action in disputed waters following the torpedoing of a South Korean warship confronts President Barack Obama with another international crisis that his administration doesn't want or need.
Although the isolated, communist North's behavior is notoriously unpredictable and sometimes seems irrational, all-out war between it and the democratic, capitalist South still seems unlikely, analysts said, given the stakes.
Nevertheless, tensions on the Korean peninsula, where some 28,500 U.S. troops provide a tripwire for U.S. military intervention if the North attacks, are likely to rise in coming days.
North Korea would likely lose any conflict with the South, but not before inflicting massive damage on South Korea's capital, Seoul, a 30-minute drive south of the demilitarized zone that's divided the two Koreas since 1953. U.S. intelligence officials estimate that some 11,000 North Korean artillery pieces are in sheltered positions within range of Seoul and probably could destroy much of the city before they could be knocked out.
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"The tensions certainly have increased," but there is no sign that North Korea is mobilizing its 1.2 million-strong military, said a U.S. defense official, who requested anonymity in order to speak more freely. "They have masses (of troops) down on the DMZ (demilitarized zone), but they do a normal shift or rotation," he said.
South Korean officials said they were bracing for fresh provocations from the North, especially at sea. On Monday, South Korean President Lee Myung-bak blamed North Korea for the March 26 sinking of the corvette Cheonan, which killed 46 of its crew, and said he was curbing trade with North Korea and banning its ships from transiting South Korean waters.
"That could get sort of ugly if (North Korean vessels) don't stop, and chances are they won't," said Art Brown, formerly the top U.S. intelligence analyst for East Asia. "It's unlikely they will do nothing. I tend to think they're not going to try Korean War, version two."
Still, Brown and other former top U.S. officials said that serious clashes between the Koreas during the past 57 years haven't led to warfare — and sometimes have provided opportunities for rapprochement.
"It's not inevitable that it will escalate," said Mitchell Reiss, who negotiated with North Korea during the Clinton administration.
Reiss said no war erupted after earlier North Korean acts that were more provocative than the sinking of the Cheonan was. Those included a 1983 bombing linked to North Korea that killed South Korean cabinet members who were visiting Burma and a 1968 commando raid on the South Korean presidential residence, the Blue House.
Lee also "didn't shoot all of his bullets, and he left some incentives on the table for the North Koreans to behave better in the future," Reiss said, pointing to Lee's decision not to pull out of a joint industrial park in the northern border town of Kaesong.
Fighting wars in Afghanistan and Iraq and pushing to improve relations with the Muslim world, Obama and his senior aides haven't made North Korea a foreign policy priority.
The North has been a prickly negotiating partner, and pulled out of so-called "six party" talks on its nuclear weapons program in April 2009 after the U.N. Security Council condemned it for a provocative missile launch.
For now, though, the Obama administration appears content to follow Lee's lead, while pressing China, North Korea's main benefactor, to rein in Pyongyang.
"I think what they've decided to do is muddle through," said Lawrence Wilkerson, who served as chief of staff to Secretary of State Colin Powell.
Wilkerson said the U.S. should keep up the pressure on North Korea, while offering the country's leaders "a deal they can't refuse" — security guarantees in return for nuclear disarmament. "That's counter-intuitive," he acknowledged.
No solution will get far without support from China, which keeps North Korea afloat with aid, including almost all of its oil and aviation fuel.
Beijing has declined to blame North Korea publicly for the sinking of the Cheonan, and has been cool to Lee's call for new U.N. sanctions.
At the close of high-level U.S.-China talks in Beijing Tuesday, Chinese State Councilor Dai Bingguo repeated the official line that China hopes all concerned will "calmly and appropriately handle the issue."
Former State Department official Susan Shirk said passivity could damage China's own interests, including its increasingly important trade ties with South Korea. Moreover, Beijing could find itself facing a harder-edged anti-North Korea bloc of the United States, South Korea and Japan.
"The Chinese have wanted to avoid a Northeast Asia divided into two blocs," said Shirk, the director of the University of California's Institute on Global Conflict and Cooperation. "Do they really want to stand against the United States and its allies?"
Why North Korea apparently chose to attack a South Korean ship may never be known for certain. A leading theory is that it was retribution for a November 2009 incident in which a South Korean vessel heavily damaged a North Korean warship.
Ailing North Korean dictator Kim Jong Il also might have approved the attack to win the military's support for his decision to name his youngest son, Kim Jong Un, 26, as his successor, Reiss said.
(Tom Lasseter contributed to this article from Beijing.)
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