No matter who wins South Korea's presidential election on Wednesday, the end is near for the hard-line policy on North Korea promoted by the departing president: the two top candidates both agree on a more moderate approach.
But the question of how much aid and investment South Korea should offer the North, and under what conditions, has become a major point of contention, one that could create discord with Washington.
The neck-and-neck race pits Park Geun-hye, the candidate of President Lee Myung-bak's conservative Saenuri Party, against Moon Jae-in, who represents the liberal Democratic United Party.
Their backgrounds are as different as those of any two Koreans could be. Ms. Park is the daughter of Park Chung-hee, who ruled South Korea with an iron fist from 1961 to 1979. Mr. Moon is a former student activist who was jailed in the 1970s for opposing Mr. Park's dictatorship.
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But both agree that Mr. Lee's policy of backing international sanctions to compel North Korea to end its nuclear programs and refraining from dialogue with the North has failed to tame its hostility toward the South. North Korea's successful launching of a three-stage rocket on Wednesday has not changed the candidates' promises to provide more generous aid to the North and to try to hold talks with its new leader, Kim Jong-un.
"The launch doesn't seem to be having much effect on the current presidential contest one way or the other," said John Delury, a professor at Yonsei University in Seoul who is an expert on North Korea. Here in the South Korean capital, not far from the North Korean border, "most people don't see this rocket launch as a security threat, for the simple reason that North Korea can use quicker and more effective short- and midrange capabilities to strike the South, if it ever came to that," Mr. Delury said.
For the Obama administration, the timing of the transition of power in South Korea is problematic. After the rocket launching, American officials talked ofimposing "Iran-like sanctions" on North Korea, suggesting curbs on investment and banking outside the country and on purchases of North Korean goods. Finding new sanctions that truly hurt will be difficult; the North is already one of the most penalized countries on earth.
But winning approval of those sanctions in the United Nations Security Council will be even more difficult if South Korea appears to be headed in the other direction. Susan E. Rice, the American ambassador to the United Nations, clashed on Wednesday with her Chinese counterpart over whether the rocket launching merited a response at all; the Chinese argued it did not. Marshaling support among United States allies will be almost impossible if a new South Korean president is announcing renewed initiatives.
"This could put us back to where we were in the Bush administration," one American diplomat said, "where the White House was going in one direction, imposing sanctions, and a South Korean president was going in the other."
President Obama and President Lee have pursued a policy of "strategic patience," isolating and penalizing North Korea for its provocations and hoping that China would rein in its ally. China never did.
"The United States is more than willing to let South Korea take the lead on North Korea — as long as it is comfortable with the general direction," said David Straub, deputy director at the Shorenstein Asia-Pacific Research Center at Stanford University. "The Obama administration will only be willing to go so far unless and until Pyongyang signals a genuine willingness to negotiate away its nuclear and missile programs on reasonable terms."