Perhaps it is his progress in fixing the North Korea crisis via Twitter, that has emboldened Donald Trump to choose now of all times, to ratchet up tensions with Tehran.

Trump's derision of what he has previously called the "worst deal ever" is characteristically inconsistent.

Even the good bit. For example, balance his contemporary position on Iran against his contention that the crisis with Pyongyang should have been resolved before the rogue state had a nuclear capability. This makes sense. Yet Trump is blind to the argument's obvious application to Iran – a country that was on the path to a nuclear capability but has agreed to stop, in exchange for sanctions being lifted, and its international bank accounts unfrozen.

While there are concerns over Iran's behaviour (mostly outside the agreement's purview, but not entirely), its nuclear retreat is a real-time, real-world example of how coordinated international pressure, coupled with a willingness to recognise legitimate, sovereign, defence and economic aims, can enhance global security.