The information fortress known as North Korea

Many speculate that the reclusive 66-year-old has been sidelined by a stroke, while the government in Pyongyang continues to release undated photos showing an active Kim, sporting his trademark bouffant, at public events.

The question of Kim's whereabouts underscores the difficulty of knowing anything conclusive about what goes on in North Korea, an isolated society with somewhat primitive technology and an obsession with forbidding any information -- even the price of rice -- to escape its borders.

For years, the autocratic Kim has cloaked his impoverished nation beneath a veil of secrecy that has defied the prying eyes of outsiders. Making a cellphone call to the outside world can be punished by death.

"Kim's approach is, 'Know thy enemy but don't let them know us,' " said Young Howard, who three years ago founded Open Radio for North Korea, a short-wave station that broadcasts two hours a day to the North from Seoul. "That means even his health is top secret. . . . His country is always in a state of war. That's his mentality."

As a result, analysts say, estimates about Pyongyang's nuclear capabilities and the scope of internal dissent at best remain semi-informed speculation.

These days, much of the information gathering on North Korea comes not from governments but private individuals and human rights groups that have managed to piece together a clandestine network of internal reporters. Some nongovernmental aid organizations return from the country with observations of what goes on there.

Erica Kang, director of Good Friends, a rights group that serves as a watchdog on North Korea, says reliable reports are scarce and must be independently confirmed to be believed.

Most North Koreans are limited to government-controlled news and are rarely allowed to travel from their hometowns.

"Nobody is too confident about information out of North Korea," Kang said. "Even the North Korean government isn't that confident of the statistics they compile."

Analysts say North Korea's closed society has proved virtually spy-proof.

"What Kim Jong Il has put together is a counter-intelligence masterpiece," said Korean historian Andrei Lankov, a lecturer and columnist at the Korea Times in Seoul. "For outsiders looking in, it's a intelligence nightmare. We don't know anything about North Korean politics and we should admit it."