The war of words Tuesday between the United States and North Korea comes against a noteworthy historical backdrop. Seventy-two years ago Sunday, the US dropped an atom bomb on Hiroshima. Seventy-two years ago today, it dropped a second one on Nagasaki.

Japanese Prime Minister Shinzo Abe urged progress toward abolishing nuclear arms as he spoke at a commemoration in Hiroshima, where about 80,000 people were killed instantly in 1945 and everything within a mile’s radius of the explosion was obliterated.

Regardless of where you stand on Truman’s decision to deploy nuclear weapons, we can all agree on the need to avoid a repeat use. But the atmosphere is increasingly edgy as the world confronts North Korea’s intensifying nuclear threat. That means world leaders must choose their words carefully. Tuesday, President Trump vowed “fire and fury” if the North took military action; the North retorted soon after that Guam would be a good target. More jostling followed.

That prompted Secretary of State Rex Tillerson to say that “Americans should … have no concerns about this particular rhetoric of the last few days.” That follows his comments, directed toward the North, that the US does not seek regime change or a military confrontation north of the 38^th parallel. Those were words issued with the full understanding of a critical reality: that verbal misunderstandings can quickly grow into something far more worrisome.