This isn’t a new problem but an acceleration of one. Weapons analysts have long worried about the “use it or lose it” pressures on political leaders early in a crisis to launch ballistic missiles with nuclear warheads, because an opponent’s missiles could wipe out some of those weapons in just 30 minutes. But what if the time needed to complete a pre-emptive strike on opposing forces is cut in half? Hypersonics are being designed to be launched from planes, submarines or ships and arrive at their targets in less than 15 minutes. Is that so fast that it might outstrip the ability of humans to act wisely and prevent a conflict that they would prefer to avoid?

In “Ran” — which Kurosawa once told an interviewer was partly meant to warn his audience of the dangers in a nuclear world — the second great battle scene graphically depicts how an accidental war might begin. Two rival sons of a warlord, each hungry for title and land, initially agree to settle their dispute. But neither is convinced that the other will remain peaceful, and they each see the other as postured to strike first. So, beneath brightly colored blue and red flags on a vast battlefield, they stumble, even against the wishes of their advisers, into a gruesome conflict.

No one knows for sure what will happen once the United States, Russia and China — or nations entangled in a regional rivalry, like India — equip themselves with sizable destructive arsenals of fast-flying missiles. The United Nations’ disarmament office has warned of heightened risks to peace. Congress last year ordered the Pentagon to produce a report by Jan. 31 on the threat of accidental war once hypersonics are deployed, but it hasn’t been turned over. So far, it seems, those in charge of hypersonics have been focused on building them, not imagining the reactions they might inspire in others.

R. Jeffrey Smith is a Pulitzer Prize and National Magazine Award-winning journalist and former foreign and national correspondent at The Washington Post. He is managing editor for national security at the Center for Public Integrity.