Hollywood loves sequels. However, audiences who applaud spectacular but shoddy movies have only themselves to blame. Their reward is further-diminished versions, in which the original’s flaws are more glaringly apparent. On Sunday, Donald Trump launched the third instalment of his buddy drama with North Korea’s Kim Jong-un, following the Singapore summit and Hanoi debacle.

The last-minute talks, at the demilitarised zone between the Koreas, made him the first sitting US president to step on to North Korean soil – “making history”, in the awed words of credulous observers (and, of course, himself). That something is happening for the first time does not make it inherently momentous. There is a reason why his predecessors never did this, just as they never met Mr Kim’s father and grandfather. It gives legitimacy and status to a state responsible for what the UN has called unparalleled human rights atrocities, and whose only diplomatic tool is its nuclear weapons programme – and does so for little obvious return.

A stunt designed by a president with an eye on re-election in 2020 did at least produce a pledge to revive working-level talks. (It is surely no coincidence that the national security adviser John Bolton, believed to have undermined previous talks, was busy in Ulaanbataar, Mongolia.) But reducing the heat is a low bar for achievement, and all the more so when Mr Trump did so much to raise the risks in the first place.

The problem remains the same as ever, and the US position looks if anything worse. Mr Trump boasted after Singapore that North Korea was no longer a nuclear threat. On Sunday he insisted Pyongyang’s missile tests in May were not missile tests. Meanwhile, Mr Kim is enjoying a good month, having just waved goodbye to Xi Jinping, after the first visit by a Chinese leader to North Korea for 14 years.

Moon Jae-in, the South Korean president, has been best supporting actor in this drama. But he did not join Mr Trump and Mr Kim for the sit-down meeting on Sunday. The first daughter and first son-in-law were hovering, however. Ivanka Trump’s international credentials were freshly burnished by the G20 summit in Japan, where she briefed on her father’s meeting with India’s Narendra Modi and, excruciatingly, attempted to break into a conversation with world leaders.

Trumpian diplomacy is in large part a show, and North Korea knows it. Pyongyang’s disrespect for US special representative Steve Biegun, and its determination to keep talks at the very top, is evident. The very best outcome might be token gestures towards denuclearisation on Pyongyang’s side and sanctions relief on Washington’s. Just as plausibly, the cycle of summits and spats may continue while North Korea continues to develop its programme. Worse, Mr Bolton and an erratic president could take us down a more alarming path again. There is more at stake here than audience dissatisfaction. Unlike moviegoers, we cannot afford to simply walk away.