South Korean Defense Chief : Hit North 1st if threatened

South Korea's defense chief called Wednesday for a pre-emptive strike on North Korea if there is a clear indication the country is preparing a nuclear attack.

Meanwhile, a state - run think tank predicted a military coup, popular uprising, a massacre or mass defections after North Korean leader Kim Jong Il dies. Kim, who turns 68 next month, is believed to have suffered a stroke in 2008.

The comments and speculation - made even as officials from the two Koreas discussed further developing a joint industrial complex in the North - were likely to anger Pyongyang, which recently threatened to break off dialogue and to attack Seoul.

North and South Korea have remained locked in a state of war and divided by a heavily fortified border since their three-year conflict ended in a truce, not a peace treaty, in 1953.

The United States, which backed South Korea during the war, has 28,500 troops stationed in the South to protect the ally against any threat from the communist North.

After a decade of warming ties, relations between the two Koreas turned frosty in 2008 with the inauguration of conservative South Korean President Lee Myung-bak, who has called on North Korea to stick to its disarmament commitments.

Recent reports of a South Korean contingency plan to handle any unrest in the isolate North raised Pyongyang's ire, with the North threatening to launch a "sacred nationwide retaliatory battle" and to cease all communication with the South.

If there is confirmation of North Korean intention to wage a nuclear attack, South Korea should "immediately launch a strike" on the North, Defense Minister Kim Tae-young said Wednesday in Seoul.

Kim, speaking at a seminar, made similar remarks in 2008 when he was chairman of South Korea's Joint Chiefs of Staff - comments that prompted North Korea to threaten to destroy the South.

Unrest in North Korea is a distinct possibility in coming years, the Korea Institute for National Unification said in a report posted on its Web site late Tuesday.

Authoritarian Kim Jong Il, believed to have suffered a stroke in 2008, probably won't survive past 2012, the think tank said - though it cited no evidence for its speculation. His death could touch off a military coup or power struggle unless he manages to stabilize succession plans soon, the report said.

Kim is believed to be grooming his youngest son to take over as leader of the nation of 24 million.

The think tank also speculated that Kim could delegate much of his authority to brother-in-law Jang Song Thaek, a member of the all-powerful National Defense Commission, until the son - now in his 20s - is able to take over power.

The North Korean leader himself succeeded his father, Kim Il Sung, in 1994 in communism's first hereditary transfer of power. The institute also said a collective leadership, or another figure, could emerge to rule the country after Kim's demise.

The speculation about the future of the impoverished, isolated country comes as envoys from neighboring nations seek to convince the regime to return to nuclear disarmament negotiations.

Pyongyang quit the six-nation disarmament talks also involving China, Japan, Russia, South Korea and the United States in anger over international condemnation of a long-range rocket launch last April. The regime carried out an underground nuclear test the following month in defiance.

North Korea has shown some willingness to return to the talks, but recently demanded that sanctions be lifted first. The North also called for a peace treaty to formally end the Korean War, saying the agreement would help end hostile relations with the U.S. and promote the denuclearization of the Korean peninsula. The U.S. has rejected the demands for a peace treaty or a lifting of sanctions.

"It would be inappropriate at this juncture to lift sanctions," Assistant Secretary of State Kurt Campbell told reporters Tuesday in Washington.

South Korea's top nuclear negotiator, Wi Sung-lac, left for the U.S. on Wednesday for talks with Stephen Bosworth, Washington's special envoy to North Korea, and other officials.

Meanwhile, South and North Korean officials continued to discuss their joint industrial complex in the North Korean border city of Kaesong, Unification Ministry spokesman Chun Hae-sung said. They also met Tuesday.

Kaesong is the most prominent symbol of inter-Korean cooperation. About 110 South Korean factories employ some 42,000 North Korean workers.