“China believes the Security Council’s response should be cautious and moderate, protect the overall peaceful and stable situation on the Korean peninsula, and avoid an escalation,” Chinese Foreign Ministry spokesman Hong Lei told journalists.

Bruce Klingner, a Korea expert at the Heritage Foundation, said: “China has been the stumbling block to firmer U.N. action and we’ll have to see if the new leadership is any different than its predecessors.”

A senior adviser to South Korea’s president said last week it was unlikely there would be action from the United Nations and Seoul would expect its allies to tighten sanctions unilaterally.

Kim Jong-un, believed to be 29 years old, took power when his father died on Dec. 17 last year and experts believe the launch was intended to commemorate the first anniversary of his death. The April launch was timed for the centennial of the birth of Kim Il Sung.

Wednesday’s success puts the North ahead of the South which has not managed to get a rocket off the ground.

“This is a considerable boost in establishing the rule of Kim Jong-un,” said Cho Min, an expert at the Korea Institute of National Unification.

There have been few indications the secretive and impoverished state, where the United Nations estimates a third of people are malnourished, has made any advances in opening up economically over the past year.

North Korea remains reliant on minerals exports to China and remittances from tens of thousands of its workers overseas.

Many of its 22 million people need handouts from defectors, who have escaped to South Korea, for basic medicines.

Given the puny size of its economy - per capita income is less than $2,000 a year - one of the few ways the North can attract world attention is by emphasising its military threat.