PYONGYANG, North Korea — Kim Jong Il, North Korea's longtime dictator who allowed his people to starve while building a vast military, has died of heart failure. His death sparked immediate concern over who is in control of the reclusive state and its nuclear program.
Citing YTN TV, Reuters also reported that North Korea test-fired a short-range missile off the country's east coast on Monday.
A "special broadcast" from the North Korean capital, state media said the 69-year-old died of a heart ailment on a train due to a "great mental and physical strain" on Saturday during a "high intensity field inspection." It said an autopsy was completed on Sunday and "fully confirmed" the diagnosis.
A spokesperson at the Unification Ministry confirmed Kim's death to NBC News. His funeral will be held on December 28.Video: What Kim Jong Il's death means for region (on this page)
Kim is believed to have suffered a stroke in 2008, but he had appeared relatively vigorous in photos and video from recent trips to China and Russia and in numerous trips around the country carefully documented by state media.
The communist country's "Dear Leader" — reputed to have had a taste for cigars, cognac and gourmet cuisine — was believed to have had diabetes and heart disease.
"It is the biggest loss for the party ... and it is our people and nation's biggest sadness," an anchorwoman clad in black Korean traditional dress said in a voice choked with tears. She said the nation must "change our sadness to strength and overcome our difficulties."PhotoBlog: Recent images of Kim Jong Il
Mindful of North Korea's nuclear weapons programs and 1.2 million-strong armed forces, South Korea put its military on alert. President Lee Myung-bak also convened a national security council meeting after the news of Kim's death.
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."
Video from Chinese state television showed residents of Pyongyang, the North Korean capital, weeping while KCNA reported people were "writhing in pain" from the loss.
President Barack Obama was monitoring reports of the death of the North Korean leader, the White House said Sunday night, adding that U.S. officials were in contact with allies in South Korea and Japan.
"We remain committed to stability on the Korean peninsula, and to the freedom and security of our allies," the White House said in a statement.Video: Even in death, details of Kim Jong Il's life elusive (on this page)
In Japan, the government said in a statement on Monday that Prime Minister Yoshihiko Noda told ministers and officials to boost information gathering on the future of North Korea and to be ready for the unexpected, Reuters reported.
Kim Jong Il inherited power after his father, revered North Korean founder Kim Il Sung, died in 1994. In September 2010, Kim Jong Il introduced his third son, the 20-something Kim Jong Un, as his successor, putting him in high-ranking posts.
Jim Hoare, a British former diplomat who served in North Korea after the countries established relations in 2000, told Sky News that Kim's death left considerable uncertainty.
"Nobody can be sure what change will be like," he said. "We don't really know who has power, who doesn't have power. We're always guessing."
Hoare said that television footage showing emotional North Koreans could be seen as "formalized grief."
"This is what people expect to do on a sad occasion," he added. "Whether they genuinely feel it, I don't know."
Asian stock markets sank Monday amid the news, which raises the possibility of increased instability on the divided Korean peninsula.Slideshow: Daily life in North Korea (on this page)
South Korea's Kospi index dived 4.1 percent but later recouped some losses to trade 3.4 percent lower at 1,777.64 by early afternoon. The Korean won fell 1.6 percent against the U.S. dollar, a traditional haven in times of uncertainty. The Japanese yen and euro also weakened against the dollar.
Japan's Nikkei 225 index was down 1.1 percent at 8,308.42, Hong Kong's Hang Seng slid 2.2 percent to 17,890.13 and the Shanghai Composite Index fell 1.6 percent to 2,188.39.
Even with a successor, there had been some fear among North Korean observers of a behind-the-scenes power struggle or nuclear instability upon the elder Kim's death.
Few firm facts are available when it comes to North Korea, one of the most isolated countries in the world, and not much is clear about the man known as the "Dear Leader."
Birth heralded by rainbows
North Korean legend has it that Kim was born on Mount Paektu, one of Korea's most cherished sites, in 1942, a birth heralded in the heavens by a pair of rainbows and a brilliant new star. Soviet records, however, indicate he was born in Siberia, in 1941.
Kim Il Sung, who for years fought for independence from Korea's colonial ruler, Japan, from a base in Russia, emerged as a communist leader after returning to Korea in 1945 after Japan was defeated in World War II.
With the peninsula divided between the Soviet-administered north and the U.S.-administered south, Kim rose to power as North Korea's first leader in 1948 while Syngman Rhee became South Korea's first president.
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The North invaded the South in 1950, sparking a war that would last three years, kill millions of civilians and leave the peninsula divided by a Demilitarized Zone that today remains one of the world's most heavily fortified. The Korean peninsula remains technically in a state of war more than 50 years after the Cold War-era armed conflict ended in a cease-fire.
In the North, Kim Il Sung meshed Stalinist ideology with a cult of personality that encompassed him and his son. Their portraits hang in every building in North Korea and on the lapels of every dutiful North Korean.
Kim Jong Il, a graduate of Pyongyang's Kim Il Sung University, was 33 when his father anointed him his eventual successor.
Even before he took over as leader, there were signs the younger Kim would maintain — and perhaps exceed — his father's hard-line stance.
South Korea has accused Kim of masterminding a 1983 bombing that killed 17 South Korean officials visiting Burma, now known as Myanmar. In 1987, the bombing of a Korean Air Flight killed all 115 people on board; a North Korean agent who confessed to planting the device said Kim ordered the downing of the plane himself.
Video: Haass: Kim Jong Il was 'tactically brilliant' (on this page)
Kim Jong Il took over after his father died in 1994, eventually taking the posts of chairman of the National Defense Commission, commander of the Korean People's Army and head of the ruling Worker's Party while his father remained as North Korea's "eternal president."
Despite scarce resources, always 'military first'
He faithfully carried out his father's policy of "military first," devoting much of the country's scarce resources to its troops — even as his people suffered from a prolonged famine — and built the world's fifth-largest military.
Kim also sought to build up the country's nuclear arms arsenal, which culminated in North Korea's first nuclear test explosion, an underground blast conducted in October 2006. Another test came in 2009, prompting U.N. sanctions.
Alarmed, regional leaders negotiated a disarmament-for-aid pact that the North signed in 2007 and began implementing later that year.
Slideshow: The life and death of Kim Jong Il (on this page)
However, the process continues to be stalled, even as diplomats work to restart negotiations.
North Korea, long hampered by sanctions and unable to feed its own people, is desperate for aid. Flooding in the 1990s that destroyed the largely mountainous country's arable land left millions hungry.
Following the famine, the number of North Koreans fleeing the country through China rose dramatically, with many telling tales of hunger, political persecution and rights abuses that officials in Pyongyang emphatically denied.
Kim often blamed the U.S. for his country's troubles and his regime routinely derides Washington-allied South Korea as a "puppet" of the Western superpower.Video: Power struggle between party, military in store for North Korea? (on this page)
President George W. Bush, taking office in 2002, denounced North Korea as a member of an "axis of evil" that also included Iran and Iraq. He later described Kim as a "tyrant" who starved his people so he could build nuclear weapons.
"Look, Kim Jong Il is a dangerous person. He's a man who starves his people. He's got huge concentration camps. And ... there is concern about his capacity to deliver a nuclear weapon," Bush said in 2005.
Defectors from North Korea described Kim as an eloquent and tireless orator, primarily to the military units that form the base of his support.
The world's best glimpse of the man was in 2000, when the liberal South Korean government's conciliatory "sunshine" policy toward the North culminated in the first-ever summit between the two Koreas and followed with unprecedented inter-Korean cooperation.
Slideshow: Journey into North Korea (on this page)
A second summit was held in 2007 with South Korea's Roh Moo-hyun.
But the thaw in relations drew to a halt in early 2008 when conservative President Lee took office in Seoul pledging to come down hard on communist North Korea.
Disputing accounts that Kim was "peculiar," former U.S. Secretary of State Madeleine Albright characterized Kim as intelligent and well-informed, saying the two had wide-ranging discussions during her visits to Pyongyang when Bill Clinton was U.S. president.
"I found him very much on top of his brief," she said.
Kim cut a distinctive, if oft-ridiculed, figure. Short and pudgy at 5-foot-3, he wore platform shoes and sported a permed bouffant.
His trademark attire of jumpsuits and sunglasses was mocked in such films as "Team America: World Police," a movie populated by puppets that was released in 2004.
Kim was said to have cultivated wide interests, including professional basketball, cars and foreign films. He reportedly produced several North Korean films as well, mostly historical epics with an ideological tinge.
Interactive: Meet North Korea’s first family (on this page)
A South Korean film director claimed Kim even kidnapped him and his movie star wife in the late 1970s, spiriting them back to North Korea to make movies for him for a decade before they managed to escape from their North Korean agents during a trip to Austria.
Kim rarely traveled abroad and then only by train because of an alleged fear of flying, once heading all the way by luxury rail car to Moscow, indulging in his taste for fine food along the way.
Lived in luxury
One account of Kim's lavish lifestyle came from Konstantin Pulikovsky, a former Russian presidential envoy who wrote the book "The Orient Express" about Kim's train trip through Russia in July and August 2001.
Pulikovsky, who accompanied the North Korean leader, said Kim's 16-car private train was stocked with crates of French wine. Live lobsters were delivered in advance to stations.
A Japanese cook later claimed he was Kim's personal sushi chef for a decade, writing that Kim had a wine cellar stocked with 10,000 bottles, and that, in addition to sushi, Kim ate shark's fin soup — a rare delicacy — weekly.
"His banquets often started at midnight and lasted until morning. The longest lasted for four days," the chef, who goes by the pseudonym Kenji Fujimoto, was quoted as saying.
Kim is believed to have curbed his indulgent ways in recent years and looked slimmer in more recent video footage aired by North Korea's state-run broadcaster.
Slideshow: The life of Kim Jong ll (on this page)
Kim's marital status wasn't clear but he is believed to have married once and had at least three other companions. He had at least three sons with two women, as well as a daughter by a third.
His eldest son, Kim Jong Nam, 38, is believed to have fallen out of favor with his father after he was caught trying to enter Japan on a fake passport in 2001 saying he wanted to visit Disney's Tokyo resort.
His two other sons by another woman, Kim Jong Chol and Kim Jong Un, are in their 20s. Their mother reportedly died several years ago.
The Associated Press, Reuters, NBC News' Julie Yoo and msnbc.com staff contributed to this report.