Where to now for the hermit kingdom?
To begin to understand the stakes underpinning North Korea's transition of power in communism's only dynasty, you only need to drive less than an hour from central Seoul. Here, as you drive through plains of mudflats and reeds, you will notice fortifications jutting out of the wilderness, or maybe a column of camouflaged soldiers stalking through the scrub.
As you arrive at the truce village of Panmunjom - a no-man's-land administered on the South Korean side by United Nations forces - the paranoid realities of the world's last cold war border are even more apparent. North Korean soldiers peer through large binoculars just metres away from their South Korean enemies, who stand, shoulders hunched and fists clenched, in a taekwondo fighting stance. The two sides, of course, are still technically at war, with the hostilities of the 1950-1953 Korean war having ended with an armistice, not a peace treaty.
For all the talk of hot issues such as the South China Sea or the India-China border, military strategists have long known there is no more dangerous place in the region.
A giant North Korean flag - reportedly the biggest in the world - ripples above a nearby village. Less visible are an estimated 70,000 artillery pieces the North has hidden in bunkers and tunnels on its side of what is the most heavily fortified border on earth. Even without the nuclear weapons it is developing, or its missiles, Pyongyang could rain thousands of artillery shells on Seoul.
Even a small spike in tensions and uncertainty as Kim Jong-un - young, untested and largely unknown - assumes the mantle of his father and grandfather would be enough to send currents of fear far beyond Seoul.
Last year's fatal torpedoing of a South Korean warship - denied by Pyongyang - and the artillery attack on the border island of Yongpyeong only underscore the dangerous sensitivities of transition in Pyongyang.
Beijing has long feared internal instability or a regime collapse that could send millions of refugees pouring into China's relatively poor northeast. Then there are the longer-term questions about the future political shape of a Korea unified on the terms of a pro-Western South.
In Japan, a country loathed by North Korea's ruling elite, there is the fear of missiles - conventional or nuclear - being directed at its cities in any power struggle or collapse. It is a concern constantly monitored by Washington, which bases the US 7th Fleet in Japan and 28,000 troops in South Korea.
And then there is Seoul itself. For all their fears of living next door to an enemy that it the world's last Stalinist hermit state, many yearn for eventual reunification with their ethnic kin. But they don't want that to come with war or chaos. Such are the societal differences that South Korean government strategists know that Korean unification would be far more difficult and expensive than, for example, the German model.
Seoul, for example, is considered the world's most technologically advanced capital in terms of the internet and communications while Pyongyang is the world's most isolated. Just as there is no way to move money electronically inside or outside of North Korea, the few mobile phones that circulate inside the country cannot be used to make international calls. Access to South Korean or other international media is strictly limited - a far different situation to that of East Germany before the fall of the Berlin Wall.
'We've got to hope, plan and pray for some kind of structured reunification,' one South Korean presidential adviser said recently. 'There are really no other workable options - the alternatives are simply too dark.'
Among the darker scenarios discussed privately in the region is not just the risk of a collapse in North Korea, but of the resulting breakdown in relations and communications across the region. Washington and Seoul constantly discuss and revise contingencies, as do Washington and Tokyo. Such high-level intelligence exchanges are growing between Seoul and Tokyo but remain at best a work-in-progress, according to a range of officials in both capitals.
But while the US and its allies talk about contingencies among themselves, there is little sharing of plans with Beijing or Moscow, irrespective of the early optimism of the unprecedented six-nation diplomatic effort to force Pyongyang to exchange its nuclear programme for aid.
'There is still too much suspicion across this region and not enough sharing of contingencies and plans when it comes to North Korea,' a Japanese cabinet adviser said. 'We have an alliance and they have a fraternal relationship.
'The worst-case scenario is not difficult to imagine should North Korea collapse. Who wants to see the PLA facing US-backed South Korean troops as both try to secure North Korea in a way that helps their own ambitions for what a unified state would look like? China can't raise these issues with Pyongyang, and it is difficult for the US and its allies to raise them with Beijing in any meaningful way. This region has been there before and no-one wants to go back down that road.'
A lot then rests on the young shoulders of Kim Jong-un and the court of his advisers apparently hand-picked by his father. Kim Jong-il, despite his hard-living, playboy reputation, swiftly displayed a ruthlessness and cunning that saw him secure his own transition after the death of his father, Kim Il-sung, in 1994. Powerful internal elites and military brass were in turn courted or purged as needed while Kim's bizarre diplomatic manoeuvres frustrated his neighbours and major powers.
It remains to be seen whether Kim Jong-un can match his father's talent for raw survival.
If the 1994 transition was difficult enough for a nervous region, this one will be more so. North Korea is now nuclear-armed, having successfully tested a nuclear explosive device in 2006. The extent of their arsenal, and whether it can be fitted with a missile warhead, remains unknown.
The stakes, then, could not be higher.
