North Korea’s latest nuclear test raises fresh concerns about how to rein in Pyongyang’s nuclear ambitions. While some experts believe Kim Jong-il, the country’s ailing dictator, is trying to shore up his family dynasty to prepare for a succession, some observers believe Mr Kim wants North Korea formally recognised as a nuclear power to gain leverage in any future negotiations with the US.

“While it’s too soon to tell what this test means over the long term, it certainly suggests that the North Korean regime isn’t serious about scaling back its nuclear programme in the near term,” said one US counter-proliferation official.