Last week's devastating train blast in North Korea has refocused attention on the murky question of leader Kim Jong-il's successor.
Kim Jong-il's succession plans are difficult to fathom
Mr Kim is believed to have passed through the station in Ryongchon, which was devastated in the explosion, just hours before the incident.
If he had been seriously injured or killed, diplomats and analysts are not sure who would have taken his place as North Korea's "Dear Leader".
It is likely that in the first instance, the nominal head of state - Kim Yong-nam, the president of the Supreme People's Assembly - would have assumed power.
Kim Jong-il was travelling back from China with a sizeable entourage, including the chief of general staff of the army, Kim Yong-chun and Prime Minister Pak Pong-ju, according to state media. But the reports did not mention Kim Yong-nam.
Kim has several children
His eldest son disgraced himself in Japan
Therefore, power may pass to a younger boy, Kim Jong-chul
Even if Kim Yong-nam had initially taken the reins, it is far from clear what would have happened next. The relationship between the military, party and Kim Jong-il's family is difficult to fathom.
There has only been one change of leadership in North Korea so far - from Kim Il-sung to his son Kim Jong-il - and that was put in motion several years before the elder Kim's death.
Kim Jong-il is himself believed to be grooming one of his sons as successor, but the candidates may be considered too young to assume power any time soon.
A recent BBC News Online investigation into the country's "first family" found that many analysts believed a serious contender was Kim Jong-chul, Kim Jong-il's oldest son by the woman thought to be his favourite consort.
But Kim Jong-chul, who works in the Party propaganda department - the same job that Kim Jong-il did when he was being groomed for succession by his father - is only in his early 20s.
A factor which may further complicate the succession question is the reported illness of Kim Jong-chul's mother, Ko Young-hee.
A former dancer in the state dance troupe, Ms Ko is currently reported to be receiving treatment in a Paris hospital, according to the Japanese newspaper Sankei Shimbun.