(BBC)The youngest son of North Korean leader Kim Jong-il has been appointed to two key party posts, in a move widely seen as part of a gradual transfer of power.
Kim Jong-un was named vice-chairman of the Central Military Commission of the Workers' Party and was appointed to its central committee, state media said.
Kim Jong-il, thought to be in poor health, was re-elected as leader at the party's first congress for 30 years.
The US said the significance of the promotions was not yet clear.
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Inside North Korea
"I would suppose this is perhaps the ultimate reality show unfolding in North Korea, and we are simply watching this very closely," said state department spokesman PJ Crowley.
Chinese President Hu Jintao sent congratulations to Mr Kim on a successful party conference - but did not mention Kim Jong-un's promotion.
Mr Hu said China would "always handle, maintain and boost China-DPRK [North Korea] relations from a strategic height and a long-term perspective ... despite the ups and downs of the international situation".
The US and China, the North's only real ally, have held regular talks with Pyongyang over its nuclear programme in recent years, and the UN has placed sanctions on the North over the issue.
