By Jack Kim
SEOUL (Reuters) - Whoever wins South Korea's December 19 presidential election will likely find that spiky and unpredictable North Korea is as ready to strike as it is to negotiate.
The main contenders in the South's election have said they would hold talks with Kim Jong-un, the youthful ruler of one of the world's most heavily armed states, in a bid to end the chill that has descended on relations under South Korea's President Lee Myung-bak, whose mandatory single term ends in February.
But the "military first" policy of late North Korean leader Kim Jong-il has outlived him and analysts say the South's next president could find his son, the third member of his family to rule, just as wily and hard to deal with.
Conservative candidate Park Geun-hye, the daughter of former dictator Park Chung-hee, says she wants to build a new "trustpolitik" between the two Koreas, which remain technically at war after an armistice ended their 1950-53 conflict.
Her main challenger, left winger Moon Jae-in, has pledged unconditional talks with the North and aid.
During his 17-year rule, Kim Jong-il took $450 million worth of government and private-sector aid from South Korea under the South's Sunshine Policy, aimed at buying peace on the peninsula.
But while taking the aid, the North pushed ahead with developing nuclear weapons and missile programs.
"However things work out, it tends to be the North that sets the agenda," said Yang Moo-jin of the University of North Korean Studies in the South Korean capital, 30 km (20 miles) from the frontier separating the prosperous South from the North, whose economy is just a fortieth the size of the South's.
Even so, thanks to Kim's "military first" policies aimed at building a strong state that the United States would have to reckon with, its armed forces are more than a million strong and could soon be brandishing deployable nuclear weapons.
The North's armed forces shelled a South Korean island in 2010 after Lee, a conservative, cut off aid, and they were also blamed for sinking a South Korean warship in the same year with the loss of 46 lives, something the North denied.
"The Sunshine Policy was supposed to allow us to take charge of the Korean peninsula's future when the Cold War ended," said Paik Hak-soon of the Sejong Institute, a Seoul-based think-tank.
"Then Lee came in and the threat of war became very real."
SON OF KIM, DAUGHTER OF PARK
Kim Jong-un initially appeared to be a very different proposition from his austere father. He speaks in public, something Kim Jong-il rarely if ever did, he is often pictured smiling, joking and accompanied by his young wife.
His policies, however, mirror his father's. The official ideology of economic, military and political self-reliance remains in place, backed up by the armed forces and what Kim Jong-il termed the "philosophy of the barrel of a gun".
In April, North Korea tore up a food-aid deal with the United States when it launched a long-range rocket which critics say is designed to test technology that could be used to design a missile to carry a nuclear warhead.
Already heavily sanctioned as a result of 2006 and 2009 nuclear weapons tests, the North is barred from developing missile and nuclear technology by U.N. resolutions.
This month, it said it would launch another rocket some time in December carrying a weather satellite, which is timed for the anniversary of Kim Jong-il's death, and coincides with elections in South Korea and Japan.
The North said on Saturday the launch could be postponed, but gave no new timeframe or reason for the delay.
The planned launch has drawn condemnation from the United States, South Korea and Japan and "deep concern" from China, the North's one major backer.
At the same time, satellite images appear to show the North is building a light water reactor and working on uranium enrichment, according to the International Atomic Energy Agency, which could allow it to expand its nuclear arsenal.
Such actions will test South Korea's next president and the North will look to exploit inconsistencies in policy.
Lee threatened strikes commensurate with "provocations" after the island shelling, which is believed to have discouraged further attacks. Park has not stated what the response would be in the event of hostile policies and weapons development.
"There need to be measures to spell out consequences ... but I don't see them," Yang said of Park's policies.
If Park does come to power, she will have to negotiate with the grandson of Kim Il Sung, the first ruler of North Korea who ordered several assassination attempts on her father, one of which resulted in her mother's death.
Moon was a top aide to former President Roh Moo-hyun who believed in engagement with the North. The prospect of unconditional aid under Moon means he is likely to appeal to the North more than Park.
She has angered the North with demands that it drop its nuclear program and missile tests and the North's media has labeled her a "fascist".
Unlike previous presidential campaigns, North Korea has not featured as a big issue, with Park and Moon focusing their attention on the economy.
(Editing by David Chance and Robert Birsel)