Questions over Kim's health highlight intelligence limits

North Korean leader Kim Jong Un's prolonged public absence has led to rumours of ill health and worries about how it could influence the future of what one analyst calls Northeast Asia's Achilles' heel, a reference to the North's belligerence and unpredictable nature.

But there's a basic, unanswered question, debated by the media and government intelligence services alike: Are the rumors even true? The exact state of Kim's health matters because it could determine the stability of the dynastic government in Pyongyang and the security of nuclear weapons that the nation has repeatedly threatened to use on its neighbors and the United States.

It's a problem that outside nations have faced for decades. Gathering intelligence on perhaps the world's most secretive, suspicious and difficult-to-read country is incredibly difficult.

And there's probably nothing North Korea guards more closely than information on Kim's health, which is only likely shared among a small portion of the elite, including his powerful sister, Kim Yo Jong.

At the heart of the intelligence shortcomings about North Korea is its extremely closed nature. But there is also plenty of blame leveled in South Korea at efforts there.

Supporters of South Korea's current liberal government, which remains eager for inter-Korean engagement, lament the previous decade of conservative rule there, when exchanges between diplomats, government and business leaders, aid groups and others stopped under hard-line polices toward North Korea's nuclear ambitions. This, they say, deprived spies of high-quality information sources.

Conservatives, on the other hand, blame liberals for supposedly downsizing espionage operations while pursuing inter-Korean rapprochement. They say such networks have been difficult to rebuild.

South Korea's government has repeatedly played down unconfirmed media reports that Kim is in fragile health following heart surgery, saying it has detected no unusual activity in North Korea or any emergency preparation by its ruling Workers' Party, military and Cabinet.

Without specifying its information sources, South Korea's presidential office said it believes Kim is handling state affairs normally at an unspecified site outside the capital, Pyongyang.

However unfounded the fears may be, some experts say South Korea, as well as its regional neighbors and ally Washington, must begin preparing for high-level instability that could come if Kim is sidelined by health problems or even dies. That could include North Korean refugees flooding South Korea or China, or military hard-liners letting loose nuclear weapons.

While those are worst-case scenarios, planning for them is crucial because nobody knows for sure what's happening inside North Korea, said Nam Sung-wook, a North Korea expert at Seoul's Korea University who termed the situation the "Achilles' heel of international politics in Northeast Asia."