Kim Jong-il, the enigmatic North Korean leader, died on a train at 8:30 a.m. Saturday in his country. Forty-eight hours later, officials in South Korea still did not know anything about it — to say nothing of Washington, where the State Department acknowledged “press reporting” of Mr. Kim’s death well after North Korean state media had already announced it.
For South Korean and American intelligence services to have failed to pick up any clues to this momentous development — panicked phone calls between government officials, say, or soldiers massing around Mr. Kim’s train — attests to the secretive nature of North Korea, a country not only at odds with most of the world but also sealed off from it in a way that defies spies or satellites.
Asian and American intelligence services have failed before to pick up significant developments in North Korea. Pyongyang built a sprawling plant to enrich uranium that went undetected for about a year and a half until North Korean officials showed it off in late 2010 to an American nuclear scientist. The North also helped build a complete nuclear reactor in Syria without tipping off Western intelligence.
As the United States and its allies confront a perilous leadership transition in North Korea — a failed state with nuclear weapons — the closed nature of the country will greatly complicate their calculations. With little information about Mr. Kim’s son and successor, Kim Jong-un, and even less insight into the palace intrigue in Pyongyang, the North’s capital, much of their response will necessarily be guesswork.
“We have clear plans about what to do if North Korea attacks, but not if the North Korean regime unravels,” said Michael J. Green, a former Asia adviser in the Bush administration. “Every time you do these scenarios, one of the first objectives is trying to find out what’s going on inside North Korea.”
In many countries, that would involve intercepting phone calls between government officials or peering down from spy satellites. And indeed, American spy planes and satellites scan the country. Highly sensitive antennas along the border between South and North Korea pick up electronic signals. South Korean intelligence officials interview thousands of North Koreans who defect to the South each year.
And yet remarkably little is known about the inner workings of the North Korean government. Pyongyang, officials said, keeps sensitive information limited to a small circle of officials, who do not talk.
“This is a society that thrives on its opaqueness,” said Christopher R. Hill, a former special envoy who negotiated with the North over its nuclear program. “It is very complex. To understand the leadership structure requires going way back into Korean culture to understand Confucian principles.”
On Monday, the Obama administration held urgent consultations with allies but said little publicly about Mr. Kim’s death. Senior officials acknowledged they were largely bystanders, watching the drama unfold in the North and hoping that it does not lead to acts of aggression against South Korea.
None of the situations envisioned by American officials for North Korea are comforting. Some current and former officials assume that Kim Jong-un is too young and untested to step confidently into his father’s shoes. Some speculate that the younger Mr. Kim might serve in a kind of regency, in which the real power would be wielded by military officials like Jang Song-taek, Kim Jong-il’s brother-in-law and confidant, who is 65.
Such an arrangement would do little to relieve the suffering of the North Korean people or defuse the tension over its nuclear ambitions. But it would be preferable to an open struggle for power in the country.
“A bad scenario is that they go through a smooth transition, and the people keep starving and they continue to develop nuclear weapons,” said Jeffrey A. Bader, a former Asia adviser to President Obama. “The unstable transition, in which no one is in charge, and in which control of their nuclear program becomes even more opaque, is even worse.”
As failures go, the Central Intelligence Agency’s inability to pick up hints of Mr. Kim’s death was comparatively minor. But as one former agency official, speaking on condition of anonymity about classified matters, pointed out: “What’s worst about our intel is our failure to penetrate deep into the existing leadership. We get defectors, but their information is often old. We get midlevel people, but they often don’t know what’s happening in the inner circle.”
The worst intelligence failure, by far, came in the middle of the Iraq war. North Korea was building a nuclear reactor in Syria, based on the design of its own reactor at Yongbyon. North Korean officials traveled regularly to the site.
Yet the United States was ignorant about it until Meir Dagan, then the head of the Mossad, Israel’s intelligence service, visited President George W. Bush’s national security adviser and dropped photographs of the reactor on his coffee table. It was destroyed by Israel in an airstrike in 2007 after the United States turned down Israeli requests to carry out the strike.
While the C.I.A. long suspected that North Korea was working on a second pathway to a bomb — uranium enrichment — it never found the facilities. Then, last year, a Stanford University scientist was given a tour of a plant, in the middle of the Yongbyon complex, which American satellites monitor constantly. It is not clear why satellite surveillance failed to detect construction on a large scale at the complex.
The failure to pick up signs of turmoil are especially disconcerting for people in South Korea. The South’s capital, Seoul, is only 35 miles from the North Korean border, and the military is on constant alert for a surprise attack.
Yet in the 51 hours from the apparent time of Mr. Kim’s death until the official announcement of it, South Korean officials appeared to detect nothing unusual.
During that time, President Lee Myung-bak traveled to Tokyo, met with the Japanese prime minister, Yoshihiko Noda, returned home and was honored at a party for his 70th birthday.
At 10 a.m. local time on Monday, even as North Korean media reported that there would be a “special announcement” at noon, South Korean officials shrugged when asked whether something was afoot. The last time Pyongyang gave advance warning of a special announcement was in 1994, when they reported the death of Mr. Kim’s father, Kim Il-sung, who also died of a heart failure. (South Korea was caught completely off guard by the elder Mr. Kim’s death, which was not disclosed for 22 hours.)
“ ‘Oh, my God!’ was the first word that came to my mind when I saw the North Korean anchorwoman’s black dress and mournful look,” said a government official who monitored the North Korean announcement.
“This shows a big loophole in our intelligence-gathering network on North Korea,” Kwon Seon-taek, an opposition South Korean lawmaker, told reporters.
Kwon Young-se, a ruling party legislator and head of the intelligence committee at the National Assembly, said the National Intelligence Service, the main government spy agency, appeared to have been caught off guard by the North Korean announcement. “We will hold them responsible,” he said.
Mark Landler reported from Washington, and Choe Sang-Hun from Seoul, South Korea. David E. Sanger contributed reporting from Washington.
The article, " first appeared in The New York Times.