By pulling out of the nuclear accord Iran signed in 2015 with the US and five other world powers, Donald Trump unshackled Tehran from a commitment it has honoured to mothball most of its nuclear programme in return for relief from many economic sanctions.

He replaced a rare triumph of diplomacy with a detonator in the most combustible region in the world, threatening allies as well as adversaries with sanctions unless they cease doing business with Iran. Within hours of his nuclear démarche, Israel and Iran traded heavy fire across the Syrian border, in the first direct confrontation between the two sworn enemies, raising the spectre of a new regional war spinning out of the vortex of a Syrian civil war that already rips through local borders.

As if this unravelling were not enough, the ultra-hawks the US president recently appointed as secretary of state, Mike Pompeo, and national security adviser, John Bolton, this week came out with their alternative to the deal struck by President Barack Obama they so revile. Not so much a Plan B as a Plan C for regime change, it is no alternative at all and surely not intended as one.