Having cause for optimism in our troubled world these days is a rare commodity. Friday’s remarkable scenes from Panmunjom of Kim Jong Un, the North Korean leader greeting Moon Jae-in, the South Korean President, was one of those occasions.

For more than six decades the two Koreas have been technically at war. Most recently the North’s nuclear ambitions have threatened to plunge the region into conflict. The current mood of rapprochement then is to be welcomed even if diplomatic caution is the order of the day.

The coming summit that will see Kim and US President Donald Trump sit down together will test two nations long suspicious of each other. Should the outcome make positive steps toward “denuclearisation” then the region would undoubtedly be a safer place. Should Trump pull off a diplomatic coup - though that is far from certain – then no doubt he will make the most of flagging up his role in that process.

Any reduction in arms would be a good thing - but with such a success would come another danger, that of normalising relations with a Pyongyang regime that continues to keep the vast majority of its citizens in what amounts to an open-air gulag. For that reason any negotiations tackling the thorny issue of North Korea’s weapons must not lose sight of the need to push equally hard for the basic human rights currently denied most North Koreans. Failure to do so, whatever gains were made regarding “denuclearisation”, would be an abandonment of our values.