Whatever else you may say about Kim Jong-il, his sense of timing is exquisite. The first time his regime tested a nuclear device, in October 2006, the underground blast coincided almost exactly with the touchdown on (South) Korean soil of Shinzo Abe, a hardline critic of Pyongyang and then Japan’s prime minister. Mr Abe duly pushed for tougher United Nations sanctions against the North. But, within weeks, plans were set in motion to bring Pyongyang back to a negotiating table where it was offered further goodies to reverse its nuclear ambitions.

This time, reports that North Korea has tested a second bomb come as South Korea is reeling from a homegrown crisis, the suicide of Roh Moo-hyun, president until last year. Roh, who jumped off a cliff on Saturday, was an advocate of the so-called Sunshine Policy of engagement with the North, a strategy that was torn to shreds by Pyongyang’s 2006 nuclear blast.