In the 1980s, when Ronald Reagan was negotiating nuclear disarmament with the Soviet Union, the US president was fond of quoting an old Russian proverb: “Trust, but verify”. That phrase might also serve as a useful motto for President Moon Jae-in of South Korea, as he prepares for his summit with Kim Jong Un, the “supreme leader” of North Korea.

Excitement about the prospect of a peace treaty and nuclear disarmament on the Korean peninsula is understandable. But the world has been here before — as has President Moon. Mr Moon was chief-of-staff to the last South Korean president to stage a summit with the north. In 2007, Roh Moo-hyun, the leader of South Korea met Kim Jong Il, the current dictator’s father. Amid fanfare, it was agreed that North Korea would freeze its nuclear programme in exchange for economic aid. There was also an outline agreement to replace the armistice that ended the Korean war in 1953 with a permanent peace treaty.

These apparent breakthroughs failed to take root. Hawks in South Korea and the US now argue that North Korea never had any intention of abandoning its nuclear programme. Doves argue that some of the blame for the failure of the 2007 agreement lies in South Korea. But that failed summit is not an isolated example. A north-south summit in 2000 was hailed as a vital breakthrough — but also led to disappointment, on both the nuclear issue and the permanent peace treaty.