Could Donald Trump’s strategy for North Korea actually work? That is the question that is inevitably raised after the dramatic visit by Kim Jong Un to Beijing.

The US president’s North Korea strategy has been fairly evident ever since he took office. Mr Trump intends to put intense pressure on North Korea to get rid of its nuclear weapons, particularly those that could directly threaten the US. To do this, Mr Trump has resorted to frequent threats of military action, talking of unleashing “fire and fury” on the North Koreans. But he has also always intended to use China, North Korea’s closest ally, to exert maximum diplomatic and economic pressure on the Kim regime. The goal is that the combination of US threats and Chinese pressure will force North Korea to back down.

On the face of it, this goal looks closer to fruition after Mr Kim’s visit to China. In a parting statement, Mr Kim pledged that the “issue of de-nuclearisation on the peninsula can be resolved”. But while that sounds promising, a theoretical commitment to scrapping nuclear weapons still leaves huge issues to be resolved. The North Korean leader’s statement also referred to “simultaneous steps for peace”, which is probably code for the longstanding North Korean demand for the withdrawal of US troops from the Korean peninsula. No US administration, to date, would have contemplated pulling out of South Korea. Mr Trump will probably maintain this US red line — although his approach to foreign policy is so unorthodox that nothing can be taken for granted.