North Korea has a long record of brinkmanship involving its weapons programmes. There are concerns it has returned to that tactic in the wake of the failure of leader Kim Jong-un’s latest summit with US President Donald Trump. American analysts believe satellite images show rebuilding work at a test site for long-range missiles that was partially dismantled as a goodwill gesture after the leaders’ first meeting. But no matter whether this is the case, the reality has always been that ending decades of animosity between the nations cannot be resolved by a few rounds of high-profile talks; it requires years of preparation, commitment and effort. Kim and Trump do not appear to have understood that before their second meeting in Hanoi. What caused it to break down early without agreement remains uncertain, both leaders and their envoys giving different accounts. But the sides left open the possibility of further talks and the United States has since cancelled two rounds of military exercises with ally South Korea that Pyongyang had viewed as provocative. A return by the North to testing weapons would not be in the spirit of the progress made so far. It would not be good for China, which has been instrumental in brokering talks, and South Korea’s President Moon Jae-in, who has helped smooth ties between the rivals. But Kim returned to Pyongyang empty-handed without a peace deal or, importantly for a nation suffering food shortages, the lifting of economic sanctions. Trump also failed to attain a deal on the North’s scrapping of its nuclear programme, denying him much-needed political capital at home. Only a supreme optimist could have expected a breakthrough, though; there are too many obstacles. The North’s military will not easily, if at all, give up weapons that took so much effort to develop. Trump has to convince numerous groups of American sceptics, among them lawmakers, human rights advocates, army generals and war veterans and their families, that Kim can be trusted. China and South Korea can help. But resolution requires more than chemistry between Kim and Trump. Their negotiators need to do the groundwork and both leaders have to be dedicated to peace.