To use a phrase for which the otherwise unlamented Donald Rumsfeld was unjustly mocked, Kim Jong Un is an Unknown Known. Until recently, Kim Jong Il’s No 3 son was an Unknown Unknown.

The first hint of his existence came in a 2003 memoir by the family’s Japanese chef. Until then, North Korea’s Dear Leader was known only to have two sons by different mothers — both of the latter now deceased and neither of whom he formally married.

Kim Jong Nam, the eldest son, blotted his copybook in 2001 when he was caught at Narita airport with a forged passport, allegedly en route to Disneyland.

Kim Jong Chul, the second son, is an Eric Clapton fan and is said to have been dismissed by his father as too effeminate — a condition variously ascribed to a hormonal disease, sexual orientation or just a putdown by his macho father. Either way, Kim Jong Chul does not cut the kimchi.

Kim Jong Il’s failure until now to anoint a successor contrasts starkly with his own careful grooming as dauphin for up to 30 years. At first denied, then coded as the Party Centre, he was finally named and acclaimed in 1980.

That gave him 14 years of experience and exposure as a quasi-prime minister while his father, Kim Il Sung, who died in 1994, was alive.

Nothing so leisurely is feasible this time. Kim Jong Il is 68; his stroke in August last year was a stark intimation of mortality. Had he died, North Korea could have been plunged into turmoil.

Kim Jong Un is young and untried. Picking him is contentious and may yet be contested. To prevent that, Kim Jong Il’s brother-in-law Chang Sung Taek — promoted in April as a rare civilian on the National Defence Commission, the top executive body — will act as his caretaker, mentor and protector.

Yet Chang may have his own ideas. His adopted son, Kim Jang Hyun — in fact a son of Kim Il Sung by one of his nurses — has been tipped as another contender. In his day, Kim Jong Il had to see off his uncle Kim Yong Ju as a competitor.

Alternatively his own able and urbane half-brother, Kim Pyong Il, posted far away in Europe for more than a decade — currently as Ambassador in Warsaw — might still be a threat.

So the April rocket and May nuclear test — the latter on the very day, or so Seoul tells us, that North Korea’s key institutions were ordered to swear fealty to Kim Jong Un — may have been as much for domestic purposes as to scare the wider world or get President Obama’s attention.

Aidan Foster-Carter is Honorary Senior Research Fellow in Sociology & Modern Korea, Leeds University

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