North Korea’s latest nuclear test has been met with the usual chorus of outrage. It showed “maniacal recklessness”, said Park Geun-hye, South Korea’s president. “Absolutely unacceptable” was the reaction of Shinzo Abe, Japan’s prime minister. China “strongly opposed” Friday’s test, according to an official statement.

There is strong emotion behind such condemnations. But they are unlikely to cut much ice with Kim Jong Un, the North Korean dictator whose militarised regime sees the US and South Korea as enemies and releases mocked-up videos of Seoul being hit by Pyongyang’s rocket attacks. Mr Kim’s fulminations have previously described Americans as “imperialist aggressors” and “cannibals” who seek “pleasure in slaughter”.

Vehement rhetoric, therefore, should not obscure the fundamental fracture within which Pyongyang’s menace has incubated. Decades of rivalry and mistrust between China and the US, the only two countries with the muscle to shape North Korea’s destiny, have thwarted any concerted attempt to impose meaningful pressure on Pyongyang to drop its nuclear programme.