Hours after coming off the phone with President Recep Tayyip Erodgan on Sunday night, President Donald Trump declared he was green-lighting Turkey’s long-threatened invasion of northern Syria.

It was a prime example of the on-the-hoof diplomacy he has come to be known for after a similar call with Mr Erdogan ended with him announcing on Twitter the withdrawal of US troops from the war-torn country back in December.

Some observers have since joked that fellow populist strongman Mr Erdogan must have a bewitching effect on Mr Trump.

The Turkish leader has for months been trying to sell the idea of a proposed “safe zone” along the southern border, most recently with an appeal to the UN General Assembly. He had hoped to collar the US president for a one-on-one on the subject after, but Mr Trump reportedly could not make time in his busy schedule.

By Sunday’s call, Mr Erdogan was seething. He expressed in it his frustration with the failure of US military and security officials to implement the agreement between the two countries on the buffer zone.