North Koreans poured into the streets on Monday to mourn the death of leader Kim Jong-il and state media hailed his untested son as the "Great Successor" of the reclusive state whose atomic weapons ambitions are a major threat to the region.
Earlier, a tearful North Korean television announcer, dressed in black and her voice quavering, said the 69-year old ruler died on Saturday of "physical and mental over-work" on a train on his way to give field guidance — advice dispensed by the "Dear Leader" on trips to factories, farms and the military.
A spokesperson at the Unification Ministry confirmed Kim's death to NBC News. His funeral will be held on Dec. 28.
Security concerns over the state, which in 2010 shelled civilians on a South Korean island and is accused of sinking one of its warships earlier that year, were heightened after Seoul said the North had test-fired a short range missile prior to the announcement of Kim's death.
It was the first known launch since June and in a bid to calm tensions, South Korea's defense ministry said it might abandon plans to light Christmas trees on the border, something the North has warned could provoke retaliation.
A U.S. official in Washington appeared to play down the missile test's significance, saying it did not seem linked to Kim's death. The official, speaking on condition of anonymity, also said the U.S. military had so far not raised alert levels for some 28,500 U.S. troops in South Korea.
President Barack Obama agreed by phone with South Korean President Lee Myung-bak to closely monitor developments.
Clinton: Hope for improved relationsSecretary of State Hillary Clinton said on Monday the United States hoped for improved ties with the people of North Korea and was in touch with its partners in the six-party nuclear talks.
"We both share a common interest in a peaceful and stable transition in North Korea," Clinton said in an appearance in Washington with visiting Japanese Foreign Minister Koichiro Gemba.
"We reiterate our hope for improved relations with the people of North Korea and remain deeply concerned about their well-being," she said.
Kim Jong Un, Kim's youngest son, was named by North Korea's official news agency KCNA as the "great successor" to his father, which lauded him as "the outstanding leader of our party, army and people."
A KCNA dispatch said North Koreans from all walks of life were in utter despair but were finding comfort in the "absolute surety that the leadership of Comrade Kim Jong-un will lead and succeed the great task of revolutionary enterprise."
But there was uncertainty about how much support the third generation of the North's ruling dynasty has among the ruling elite, especially in the military, and concern he might need a military show of strength to help establish his credentials.
"Kim Jong-un is a pale reflection of his father and grandfather. He has not had the decades of grooming and securing of a power base that Jong-il enjoyed before assuming control from his father," said Bruce Klingner, an Asia policy analyst at the Heritage Foundation in Washington.
'Writhing in pain'Video showed residents of Pyongyang, the North Korean capital, weeping while KCNA reported people were "writhing in pain" from the loss.
Large crowds gathered at a massive memorial of Kim Il-sung in central Pyongyang. Kim will be laid to rest next to his father, KCNA said.
On the streets of the North Korean capital, people wailed in grief, some kneeling on the ground or bowing repeatedly. Children and adults laid flowers at key memorials.
A tearful Kim Yong Ho said Kim Jong Il had made people's lives happier. "That is what he was doing when he died: working, traveling on a train," he said.
News of the death of the man whose push to build a nuclear arsenal left the North heavily sanctioned and internationally isolated, triggered immediate nervousness in the region, with South Korea stepping up its military alert.
In Seoul, residents worried about instability in the North. A parliamentary official, Lee Kyu-yun, said he was thinking of stocking up food in case of soaring military tensions.
Lee Byung-joon, 27, feared South Korea might have to fight a war against the North if high-ranking officials challenge the inexperienced Kim Jong Un.
"I definitely think the chance of war breaking out between the South and the North is higher now than before," Lee said.
China, the North's neighbor and only powerful ally, said it was confident the North would remain united and that the two countries would maintain their relationship.
"We were distressed to learn of the unfortunate passing of (Kim) ... and we express our grief about this and extend our condolences to the people of North Korea," Foreign Ministry spokesman Ma Zhaoxu was quoted by Xinhua news agency as saying.
"We are confident the North Korean people will be able to turn their anguish into strength and unify as one," he said.
There was less regret from some Western leaders, with Canadian Prime Minister Stephen Harper saying Kim had "violated the basic rights of the North Korean people for nearly two decades." Both he and British Foreign Secretary William Hague said they hoped North Korea's fortunes might now improve.