Donald Trump’s strategy towards North Korea is such a failure that a different US tack is obviously needed. Sanctions and threats have not prevented Kim Jong-un’s regime from developing rockets apparently capable of carrying nuclear warheads to the American mainland, as last week’s second successful test of an intercontinental ballistic missile showed. The US leader’s response was yet more criticism of Beijing for not doing enough to stop Pyongyang’s weapons programmes, further testing of a missile defence system and the flying of bombers over the Korean peninsula, all in the wake of yet more sanctions approved by the US Congress.

That leaves only three options – stronger defences, military conflict or dialogue. The United States and its ally, Japan, have stepped up pressure on China to impose tougher sanctions and Trump is reportedly looking at trade measures against Beijing to force action. But security on the Korean peninsula and beyond and trade between China and the US are unrelated issues. Sanctions do not work; Kim has flouted with impunity those imposed against his country by the United Nations and others, enabling uninterrupted weapons development. As China’s ambassador to the UN, Liu Jieyi, pointed out, it is primarily up to Washington and Pyongyang, not Beijing, to reduce tensions and find a solution.

Last month, the liberal politician reversed the position of his disgraced predecessor, Park Geun-hye, by offering North Korea negotiations to end hostilities along their heavily armed border and a fresh round of reunions of families separated by the war. His latest decision jeopardises such overtures and potentially puts at risk talks with President Xi Jinping (習近平) expected for later this year.