North Korean leader Kim Jong Il is taking advantage of Beijing's desire for stability on the Korean peninsula by engaging in provocative actions that could permanently alter the north-east Asian security situation. Mr Kim's moves are calculated – they are designed to help secure a dynastic succession and North Korea's status as a nuclear weapons power. Fearful of a flood of refugees should Mr Kim's regime implode, China has responded cautiously. Beijing apparently still believes that its national interests are best served by a weak North Korean regime that is dependent on China.

The clearest signal of Mr Kim's intentions came in an editorial published in the authoritative party daily, Rodong Sinmun, on his 67th birthday in February. It states that the future of North Korea depends on a “brilliant succession” of the “bloodline of Paektu”. Paektu is the sacred mountain where Mr Kim is said to have been born. The long-range missile test on April 5 appears to have been timed to occur just before Mr Kim promoted his brother-in-law, Chang Sung-Taek, to the powerful National Defence Commission. Mr Chang now appears at Mr Kim's side on most occasions and he appears destined for the role of regent to Mr Kim's youngest son.

The new nuclear and missile tests are just part of a series of provocative moves by Pyong-yang this spring, but even by North Korean standards Mr Kim's actions since April are outrageous. Yet China's response has been very restrained. It argues that the best option for stability in North Korea is a smooth transition of power. It therefore is hesitant about supporting sanctions that really bite, such as cutting the supply of oil and coal, which would cripple the dysfunctional North Korean economy. True, such measures could destabilise the regime. But tough, targeted sanctions may get North Korea back to the negotiating table if done with a clear offer of resuming the principles of reciprocal action embedded in the February 2007 agreement. North Korea is not Iran. It does not have oil and gas to sell to get around sanctions. If left unchecked, surely Pyong-yang will try to define a new reality that allows it to maintain nuclear weapons. Which is more destabilising: instability in succession or North Korea seeking to redefine the nuclear status of the Korean peninsula? That is the real question of instability before China.