America did not elect Elon Musk. Yet he is acting as Donald Trump’s de facto co-president. Musk’s self-appointed remit includes gunning for regime change in allied democracies. He has repeatedly said only the far-right Alternative for Germany (AfD) can save Germany in next month’s election. He is calling for an end to Sir Keir Starmer’s Labour government in the UK. And he has asked his 211mn X followers if “America should liberate the people of Britain from their tyrannical government”. The consensus seems to be yes.

It would be an understatement to say there is no precedent for such a relationship between America’s president and the world’s richest man. History offers no guidance on this kind of duet, let alone the money half of it openly gunning for the overthrow of allied governments. America’s robber barons — the Rockefellers, Vanderbilts and Carnegies — did not act as co-equals with the presidents of their day. Nor did their fabled wealth compare to Musk’s. JP Morgan was worth $49bn in today’s dollars. Henry Ford, who also had a soft spot for European fascism, was closer to $200bn. Musk’s wealth is more than double that. Ford was not admired by Franklin Roosevelt, his White House contemporary.

By contrast, the past is strewn with instances of America interfering in other countries’ politics. With the exception, however, of the CIA’s postwar bag of tricks to keep communists from power in continental Europe, Washington’s meddling has excluded allies. The question facing governments in Berlin, London and probably Paris soon is how to respond to this novel threat. Is Musk speaking for Trump? In which case, the west is as good as dead. Or is he testing the waters? That would give western capitals scope to exploit differences between Trump and Musk. The answer is probably a mix of the two.