Kerry's Hiroshima visit is a step forward in global relations

John Kerry became the most senior US official to visit the city since it was almost annihilated by an American nuclear bomb in 1945.

Some 140,000 people were killed in the horrific attack, which was followed days later by another atomic blast at Nagasaki.

The justification for the blasts is that they ended the war, and so saved hundreds of thousands of lives that would have been lost in an allied invasion of Japan.

That analysis is largely, but not entirely, accepted in Britain and America. Certainly no serious pundits deny that Germany and Japan were aggressors in World War Two and needed to be stopped by extreme measures.

The fact remains, however, that women and children and vulnerable people including the elderly were massacred on an unimaginable scale.

The world would never be the same after those two days in August 1945. It might well be that glimpsing the reality of nuclear war has ensured that no other regime, no matter how demented, has ever dared to use them again.

But in an age of utterly crazed groups such as Isis, we cannot ever drop our guard at the threat of nuclear Armageddon.

Mr Kerry did not travel alone to Japan. His presence was in the deliberately diluted context of a joint visit with other G7 foreign ministers including Britain’s Philip Hammond.

Nonetheless, his presence was a symbol of reconciliation.

Japan has reacted with great dignity to the loss at Hiroshima and Nagasaki. Like Germany, it is a nation that has mostly repudiated its war actions (although not to the extent that some of its victims, including British servicemen, would want it to).

Mr Kerry said of the peace memorial: “Everyone in the world should see and feel the power of this memorial.”

Like Auschwitz, the remnants stand preserved as a reminder of the fragility of civilisation.