If the 2015 nuclear pact cannot be rebuilt or a new one struck, then the choice will be to let Iran have the bomb or to bomb Iran

Next week the Bulletin of the Atomic Scientists will unveil the current time on its Doomsday Clock, meant to convey the nuclear dangers facing the world. The closer the clock is to midnight, the greater the existential threat. If the stand-off between Iran and Donald Trump persists, or takes a frightening turn for the worse, then the clock’s hands may be closer to the bell tolling than they have ever been. This would mean the danger to the planet was judged greater than at any time since the first H-bomb tests.

The drumbeat of war reverberates around the Middle East. On Tuesday, Britain, France and Germany said that they had been “left with no choice” but to trigger a dispute mechanism in the six-nation nuclear deal with Iran after Tehran declared, in the aftermath of the US assassination of its top general, that it would no longer observe the pact’s “operational restrictions”. Iran’s president then warned that European soldiers in the Middle East “could be in danger”, a clear indication that if the continent stood with Mr Trump then its forces could expect to be treated as enemy combatants.