If Donald Trump this week tries to bury the deal Iran reached in 2015 with the US and five other world powers, to mothball most of its nuclear programme in exchange for economic sanctions relief, it will be his most gratuitously destructive action to date.

Trying (and failing) to destroy Obamacare without anything feasible to replace it was vandalism. Pulling the US out of the Paris climate change accord is cosmically irresponsible, yet offset by the determination of American states and companies to meet the pact’s emissions targets. But to reopen the Iran nuclear deal is to open a strategic Pandora’s box — and Mr Trump is no strategist.

Not the least remarkable aspect of the Trump administration’s Iran policy mess is that the generals surrounding the president — who are deeply hostile to Iran — all favour sticking with the nuclear deal, the so-called Joint Comprehensive Plan of Action (JCPOA). Jim Mattis, US defence secretary and former commander in the Middle East, told the Senate last week that: Iran was in compliance with the deal; the JCPOA was in the US national interest; and the administration should stick with it. The week before that, General Joseph Dunford, chairman of the joint chiefs of staff, told the Senate the deal was working, and delaying any eventual Iranian development of nuclear arms.