Imagine looking in a mirror and seeing not your own reflection but that of Donald Trump. Each time you contort your face, you simultaneously contort his. You smile, he smiles. You scowl, he scowls. You control, in real time, the face of the president of the US.

That is the sinister potential of Face2Face, a technology developed by researchers at Stanford University in California that allows someone to transpose their facial gestures on to the video of someone else.

Now imagine marrying that “facial re-enactment” technology to artfully snipped audio clips of the president’s previous public pronouncements. You post your creation on YouTube: a convincing snippet of Mr Trump declaring nuclear war against North Korea. In the current febrile climate, the incendiary video might well go viral before the White House can scramble a denial.