Editor's Note: North Korea's enigmatic leader Kim Jong Il - who, after succeeding his father 17 years ago, captained his poor, closed nation and antagonized its enemies - is dead, state media reported Monday. Kim, 69, died at 8:30 a.m. Saturday, state media reported.
A broadcaster reported that Kim died due to "overwork" after "dedicating his life to the people." Kim died of "great mental and physical strain" while in a train during a "field guidance tour," North Korea's state-run KCNA news agency reported.
As North Koreans face an uncertain future without Kim Jong Il, the world's attention now turns to his son Kim Jong Un, whom the ruling Workers' Party has dubbed the "great successor." Little is known about him in the West; he is believed to be in his late 20s or early 30s.
[Updated at 8:35 a.m. ET Monday] The chairman of the U.S. joint chiefs of staff, Army Gen. Martin Dempsey, said one of the U.S. military's priorities following news of Kim Jong Il's death is to monitor North Korea's troop movement. So far, no movement of North Korea's forces has been noted, Dempsey said, according to CNN's Barbara Starr.
A short-range missile test that North Korea conducted Monday - reported earlier by South Korean media - was not a surprise and is not of particular concern, Dempsey said. South Korean media have reported that South Korean government officials do not believe the test was related to Kim Jong Il's death.
[Updated at 7:56 a.m. ET Monday] Stocks in Asia slumped on Monday amid fears that Kim Jong Il's death could lead to instability on the divided Korean peninsula.
Japan's Nikkei lost 1.3%, the Hang Seng in Hong Kong slid 1.2%, and the Shanghai Composite shed 0.3%. South Korea's Kospi fell the most, plunging 4.9% in mid-morning trading in Seoul, before climbing slightly to end 3.4% off.
Asian stocks already were battered by fears that possible credit downgrades in European countries could derail a solution to the eurozone debt crisis.
[Updated at 7:36 a.m. ET Monday] Victor Cha, senior adviser and Korea chair of the Washington-based Center for Strategic and International Studies, said Kim Jong Un will be succeeding his father in "less-than-ideal conditions," in part because he has had little time to prepare for leadership.
Whereas his father was groomed for leadership for more than a decade, Kim Jong Un - who is Kim Jong Il's third son - seems to have been positioned as successor only recently. Though he was named a four-star general last year, he never served in the military - something that has bothered some North Korean military commanders, Cha said.
Cha, a former White House National Security Council member and an expert on North Korea, said that in North Korea's system, a new ideology is supposed to come from new leadership. No ideology from Kim Jong Un has been publicly released, Cha said.
It is hard to say whether a struggle for succession will ensue, Cha said, because the Kim family has been like royalty in North Korea, though it is unclear how much support Kim Jong Un will have.
Bill Richardson, former U.S. ambassador to the United Nations, also said it wasn't clear whether Kim Jong Un will take power uncontested. He noted that North Korea's Workers Party acknowledged in a statement that Kim Jong Un is the designated successor - a sign that the power structure is coalescing around him.
[Updated at 7:01 a.m. ET Monday] North Korea test-fired a short-range missile into the Sea of Japan on Monday morning, South Korean media reported.
An unnamed South Korean government official said â€śthis is something the (South Korean) military had been keeping track of for some time, and I believe it is unrelated to the death of Kim Jong Il,â€ť South Korea's Yonhap news agency reported.
[Updated at 6:29 a.m. ET Monday] Asked if North Korea will see a succession struggle, Jim Walsh, an international security expert with Massachusetts Institute of Technology's Security Studies Program, said the situation was hard to predict. Kim Jong Un's father began grooming him for the job only three years ago after the father suffered a stroke.
In contrast, Kim Jong Il himself was groomed over a period of 14 years before taking the reins from his father, Kim Il Sung, in 1994. Even then, Walsh said, it took a year or two for Kim Jong Il to consolidate power, Walsh said.
[Updated at 6:23 a.m. ET Monday] Jim Walsh, an international security expert with Massachusetts Institute of Technology's Security Studies Program, says North Korea's transition of leadership will be a "delicate time to get through," in part because young successor Kim Jong Un will be looking to establish himself.
One of a regime's first thoughts upon the death of a leader is about whether enemies will take advantage of the situation, Walsh said. Walsh said North Korea will want to show strength, and he noted that South Korea's military reacted to Kim Jong Il's death by going on high alert.
"If you're in (North Korea's capital of) Pyongyang, that looks like threatening behavior ... so this is going to be a delicate time to get through,â€ť Walsh said.
[Updated at 5:50 a.m. ET Monday]Â South Korea's President Lee Myung-bak, at an emergency Cabinet meeting Monday to discuss the government's response following the death of Northern Korean leader Kim Jong Il, said that peace and stability on the Korean peninsula "should not be threatened by what has happened."
"We must make thorough preparations to maintain peace and stability and continue to work closely with the international community,â€ť the South Korean president said.
[Updated at 4:29 a.m. ET Monday]Â Seoul put South Korean forces on high alert and Pyongyang urged an increase in its "military capability" as the death of North Korea's enigmatic leader Kim Jong Il spurred fresh security concerns in the tense region.
A tearful state TV broadcaster reported Kim's death Monday. She said the 69-year-old leader died Saturday due to "overwork" while "dedicating his life to the people."
North Korea's official KCNA news agency said Kim suffered "great mental and physical strain" while on a train during a "field guidance tour." Kim, who had been treated for "cardiac and cerebrovascular diseases for a long period," suffered a heart attack on Saturday and couldn't be saved despite the use of "every possible first-aid measure," according to the agency.
In the country where Kim was revered as "dear leader," passers-by wept uncontrollably on the streets of Pyongyang.
[Updated at 3:19 a.m. ET Monday]Â The death of the North Korean leader Kim Jong Il has ushered in a period of tremendous uncertainty in Northeast Asia, with every move by countries in the region risking unpredictable reactions from others.
South Korea ramped up its level of military alert Monday following the announcement of Kim's death, while Japan held emergency military meetings. The United States said it was in close contact with the South Korean and Japanese governments.
"It's a moment that's rife for miscalculation and unintended consequences," CNN's Wolf Blitzer said.
The region is a combustible geopolitical mix. The South, which has the support of the United States, and the nuclear-armed North, allied with China, have technically remained at war since the conflict that split the peninsula in the 1950s.
Even before Kim's death, tensions had spiked between the two Koreas last year. The North was accused of sinking a South Korean naval vessel in the Yellow Sea and fired artillery at a South Korean island in November 2010, killing two civilians.
But the United States and other parties had appeared to make progress in recent weeks to try to rekindle negotiations over the North's nuclear program, known as the six-party talks.
Those efforts now seem to have been in vain.
[Updated at 2:48 a.m. ET Monday] As North Koreans face an uncertain future without Kim Jong Il, the world's attention now turns to his son, whom the ruling Workers' Party has dubbed the "great successor."
"Kim Jong Un's leadership provides a sure guarantee for creditably carrying to completion the revolutionary cause ... through generations," the letter said.
But little is known about the deceased leader's youngest son. Even his age is uncertain to most of the outside world: he is believed to be in his late 20s or early 30s.
[Updated at 2:14 a.m. ET Monday] A message to North Koreans posted on state-run news agency KCNA after the death of Kim Jong Il that is an emotional tribute to his life and looks at what lies ahead of North Korea.
The heart of Kim Jong Il stopped beating, but his noble and august name and benevolent image will always be remembered by our army and people and his glorious history of revolutionary activities and undying feats will remain shining in the history of the country forever."
[Updated at 1:56 a.m. ET Monday] As news of Kim Jong Il's death spread across the globe it also spread across social media. The news trended globally, with both poignant and mocking comments.
But even three hours after the news, Kim Jong Il was still trending globally and in nearly every country, according to this visualization from TrendsMap.com.
[Updated at 1:41 a.m. ET Monday] Shannon Van Sant, a journalist and documentary filmmaker who has followed missionaries and refugees that have fled the country, said she expects there will be a lot of eyes on the country's border in the coming days because of concerns about whether North Korea may see an influx of refugees fleeing through China.
â€śI think the top concern for China over the next few months is to stabilize that and try to stem any influx of North Koreans along the border," she said.
Van Sant has spoken to missionaries that said many refugees will be reluctant to speak out about what they may do, or whether they would consider returning ever. Van Sant said that even after theyâ€™ve escaped, the refugees she has met are still very scared for the safety of their family members that remain in North Korea.
"Judging from my interviews I think they hope desperately that North Korea will change to the extent that there is enough food to eat, that there aren't any executions," she said.
[Updated at 1:27 a.m. ET Monday] A message to North Koreans, posted on state-run news agency KCNA, referred to Kim Jong Un - the son of late leader Kim Jong Il - as "the great successor to the revolutionary cause ... and outstanding leader of our party, army and people."
The statement added: "Kim Jong Un's leadership provides a sure guarantee for creditably carrying to completion the revolutionary cause ... through generations."
[Updated at 1:22 a.m. ET Monday] U.S. President Barack Obama spoke with South Korean President Lee Myung-bak early Monday to discuss the situation on the Korean Peninsula following the death of North Korean leader Kim Jong Il, the White House said in a statement.
"The President reaffirmed the United States' strong commitment to the stability of the Korean Peninsula and the security of our close ally, the Republic of Korea," the statement said. The two leaders agreed to stay in close touch as the situation develops and agreed they would direct their national security teams to continue close coordination."
[Updated at 1:21 a.m. ET Monday] CNN's Stan Grant, reporting from Beijing, said because of North Korea's tight grip over information it is unknown really how much of the transition of power to Kim Jong Un has been already been fully planned by the country.
"Survival of the regime is paramount to orchestrate this [transition.]" Grant said.
Grant said that one of the big questions surrounds Kim Jong Un is that so little is known about him. And that means it makes it more difficult to know what he might do, or be able to do.
"Itâ€™s just a question mark. What do we know about him? His age?" Grant said. "Weâ€™ve heard rumors that he was schooled in Switzerland â€¦ that he is familiar with the west, but we still donâ€™t know a lot about him. We donâ€™t know how much authority he will carry."
Grant said that along those lines, it will be key to see how the youngest son will impose his own authority or whether the military will be asserting itself more.
[Updated at 12:53 a.m. ET Monday] Japanese Chief Government spokesman Osamu Fujimura said "we express our condolences on the news of passing Kim Jong Il, the chairman of the National Defense Committee of North Korea."
"We wish the sudden news would not affect North Korea negatively,"Â Fujimura said during a news conference.
CNN's Tokyo Producer Yoko Wakatsuki said Fujimura held the presser in the wake of an emergency meeting on national security upon the leader's death. He said Japan learned about Kim's death via North Korea's state
television national broadcast announcement and the Japanese government will discuss the situation in greater detail in a meeting with relevant officials at 3:00 p.m. (1:00 a.m ET.)
Japanese Prime Minister Yoshihiko Noda held an emergency meeting with the national security council during which Noda ordered his ministers to get as much info on Kim Jong Il's succession and successors as possible.
Noda told the ministers to be ready for unexpected situations,Â and keep close contact with the U.S., China and South Korea, according to the prime minister's office.
South Korea's Kospi Index fell 4.9% to 1,750.60 in mid-morning trading in Seoul before climbing slightly to 1,766,82 to be 4% off by midday.
Key stocks tumbled, with Samsung Electronics, the largest stock on the Kospi, falling 3.5% and LG Display, the world's second largest panel maker, down 7.2% in early trading.
Already battered by fears that possible credit downgrades in European countries could derail a solution to the euro zone debt crisis, Asian markets fell across the board.
At the open, Japan's Nikkei 225 index was down 1.1 % at 8,304.47, Hong Kong's Hang Seng slid 2.5%t to 17,833.42 and the Shanghai Composite Index fell 2.6% to 2,167.68.
June Park, senior economist at Meritz Securities, told Reuters.com the death of Kim Jong Il had rattled investor confidence.
"This is definitely negative factor for markets with no detailed information on his death. It will drive the stock markets lower and the Korean won to depreciate sharply as geopolitical risks are rising and foreign investors could withdraw money out of South Korea," she said.
[Updated at 12:42 a.m. ET Monday] South Korea's National Police Agency has ordered police across the country to be on emergency work shifts.
"South Korea's concern is warranted, frankly, because an insecure North Korea could well be an even more dangerous North Korea," a U.S. official said.
[Updated at 12:36 a.m. ET Monday] In response to Kim Jong Il's death, North Korea's national funeral committee said Monday, "We should increase the country's military capability in every way to reliably safeguard the Korean socialist system and the gains of revolution."
[Updated at 12:29 a.m. ET Monday] Han Sung Joo, the former South Korean ambassador to the United States, said that people across South and North Korea are watching carefully what is happening in Pyongyang following the death of leader Kim Jong Il.
"The people of course are very much interested in what is going on," he said. "The stock market is getting a beating [because of the uncertainty.]"
Han Sung Joo said that he was surprised at the news of The Dear Leader's death.
"He looked quite well in the picture that was taken only two days before his supposed death," Han Sung Joo told CNN. "So of course, sudden death can happen, but this was certainly unexpected. There was expectation that he might pass away within a few years, but I donâ€™t think North Korea itself was prepared for this early happening of the death."
He said that could be seen in the fact that it took Pyongyang two days to announce the leader's death.
"They are trying to put up a face that is both orderly and united," he said. "Predictability is better than chaos and right now it seems that North Korea the leadership in particular is trying to demonstrate they have an orderly succession process. They were not the same as when Kim Jong Il took over, because he had 20 years to prepare where Kim Jong Un had only two or three years. "
[Updated at 12:23 a.m. ET Monday] Late North Korean leader Kim Jong Il's coffin will be placed at the Kumusan Memorial Palace in Pyongyang, with mourners being received from December 20 to 27, state media reported.
[Updated at 12:15 a.m. ET Monday] The flag at the North Korean embassy in Beijing was lowered as a sign of mourning for Kim Jong Il.
[Updated at 11:56 p.m. ET Sunday] CNN Chief International Correspondent Christiane Amanpour said she remembers in 2008 when negotiations were going on between U.S. and North Korea that was seen as "a moment of hope, which rapidly came to a halt."
"That's when some people believed he had a stroke and negotiations fell apart," she said.
As for how the youngest son may fare as a leader of North Korea, Amanpour said she is not sure he can keep up with his father or his grandfather.
"Even Kim Jong Il was not able to keep the cult of personality that his father did," she said. "When Kim Jong Il nominated his son, people had concerns. [And] he's going to be taking over a nuclear nation. We will have to wait and see."
Among the things people will be watching, Amanpour said, is whether he will promote the hardline policies from the old guard, whether those people will circle the wagons around Kim Jong Un.
[Updated at 11:56 p.m. ET Sunday]Â South Korean's military raised its alert status to the middle of three levels Monday, the Ministry of Defense said.
The nation's military will closely monitor North Korean troop movements and tighten its security on the sea front with North Korea, according to the ministry. Police across the country have been ordered to be on emergency work shifts, National Police Agency said.
[Updated at 11:56 p.m. ET Sunday] CNN's Stan Grant, reporting from Beijing, said that China and North Korea likely have had contingency plans in place for the death of leader Kim Jong Il.
"When you have heightened tensions and a history of conflict" you want to make sure to be as clear in communicating with countries that have an interest in the leader's death, Grant said. "And that's where problems arise."
Grant referred to recent misunderstandings with South Korea during war games.
"We need to focus on the possibility of misunderstanding," he said.
That, he said, will be important as the country tries to move forward after the death of Kim Jong Il.
Grant said that some of the eccentricities associated with Kim Jong Il were "undeniable."
"He saw himself as a film maker. He used to bring his personal chefs in to cook his own delicacies. He had a fear of flying, only liked to travel by plane," Grant said. "But we can't just seem him through that prism. We have to seem as someone who has survived."
"The primary business of the regime is survival," Grant said.
He noted that part of the legacy of the regime for outsiders has been seen as a man at the helm of a rogue regime.
"The hermit kingdom that was cut off from the rest of the world," he said, noting how the country is sometimes described.
[Updated at 11:41 p.m. ET Sunday] Han Park, Director of the Center for the Study of Global Issues at the University of Georgia, said he expects the succession process will likely be a smooth one for North Korea.
"King Jong Il has been more of a symbolic figure," he said, noting that the process has been one in place and transitioning for years now.
Park said he doesn't believe the country will change dramatically under new leadership.
"As long as North Korea is still in the same security situation, I think you can expect the same thing under Kim Jong Un," he said. "However I think Kim Jong Un would very much be faster to develop the economy more than anything else. Because Kim Jong Il kind of wanted his son to become like China's Deng Xiaoping."
Park said despite concerns from the international community he doesn't expect there to be uprisings in the country similar to what we have seen during the Arab Spring uprisings and ousting of leaders in the Middle East and Northern Africa.
"I don't think it will invite any type of mass uprising," he said. "I think it is so important .. that Washington and Seoul not to overreact to this."
[Updated at 11:41 p.m. ET Sunday] The death of North Korean leader Kim Jong Il "brings extraordinary change and uncertainty to" the nation, a U.S. official said.
"South Korea's concern is warranted, frankly, because an insecure North Korea could well be an even more dangerous North Korea," the official said.
[Updated at 11:36 p.m. ET Sunday] Analyst Mike Chinoy told CNN that he expects funeral preparations will begin in the country which is facing a "huge shock psychologically" from the death of Kim Jong Il.
In the next few days, Kim Jong Il's son will be working on the funeral for his father, but will also be preparing for what role he will play in the country's future.
"He is clearly the designated successor," Chinoy told CNN.
"The fact that a year ago in October that Kim Jung Un was unveiled at this big meeting ... I think would indicate that the ruling elite across the board are more or less agreed on this succession," he said. "The deeper questions come long-term about the leader's son and what he will do for the country and whether he will be a figurehead or not."
[Updated at 11:34 p.m. ET Sunday]Â The office of South Korean President Lee Myung-bak said the president has canceled his afternoon schedule and "all civil officers (are) on emergency alert now.
[Updated at 11:15 p.m. ET Sunday] The White House released the following statement Sunday night in reaction to the news of the death of North Korean leader Kim Jong Il: "We are closely monitoring reports that Kim Jong Il is dead. The President has been notified, and we are in close touch with our allies in South Korea and Japan. We remain committed to stability on the Korean peninsula, and to the freedom and security of our allies."
[Updated at 10:59 p.m. ET Sunday] Kim Jong Il's funeral will be held December 28 and the national mourning period extending until December 29, North Korea's state-run KCNA news agency reported.
[Updated at 10:12 p.m. ET Sunday] North Korean leader Kim Jong Il is dead, North Korean state TV said Monday. Kim, 69, died at 8:30 a.m. Saturday, state media reported.
The son of Kim Il Song, the founder of the communist nation, Kim Jong Il had been in power since 1994 when his father died of a heart attack at age 82.
The enigmatic leader was a frequent thorn in the side of neighboring South Korea, as well as the United States. There have been reports in recent years about his health, as well as that power will be transitioned to his son, Kim Jong Un.
South Korea's military declared an "emergency alert" following Kim's death, according to Yonhap, South Korea's news agency.