It is a political cliché that tails sometimes wag dogs. The metaphor isn’t instantly decipherable though. Politics has no shortage of figurative fauna – from snakes in the grass and stalking horses to big beasts and dinosaurs – but a wagged dog is more complex than it sounds.

When first recorded in the 19th century, the idea was simple enough. A dog wagged by the tail described a situation in which an otherwise minor factor determined major decisions. But the emphasis has shifted since the release of Barry Levinson’s 1997 film. In Wag the Dog, a US president seeking re-election is embarrassed by a sex scandal and enacts a fake war in TV studios to give voters something else to worry about. A few months later, Bill Clinton ordered real-world missile strikes on Sudan and Afghanistan three days after reluctantly acknowledging his ‘inappropriate relationship’ with Monica Lewinsky – and journalists drew parallels with the movie so often that the meaning of its title mutated. The focus is no longer on the over-mightiness of a tail, but on abuses of power that draw attention away from personal wrongdoing.

The metaphor doesn’t comfortably wear the newer meaning. While a canine controlled by its rear end easily symbolises a topsy-turvy command structure, a creature that freakish doesn’t operate inconspicuously. As the shouting match between Donald Trump and Kim Jong-un escalates, the risks of the personal turning political are rising again – and the consequences this time might be not merely excessive, but apocalyptic. To mangle Borges’s remark about the Falklands War, the bald men are now fighting with thermonuclear combs; and, unlike most of his predecessors, Trump seems no more alarmed than Kim about bringing on Armageddon. That isn’t for want of information: as he revealed at his first solo press conference, he has ‘been briefed’ that ‘nuclear holocaust would be like no other.’ He sounds, nonetheless, preternaturally unconcerned. Indeed, he has publicly contemplated atomic strikes so often that it’s becoming hard to tell where Trump's pseudo-art of the deal ends and Strangelovian logic begins.

Among the many tails that could wag that dog, there is one that demands particular notice. While Trump generally enjoys feuding – so much so that he has recently added the National Basketball Association, the National Football League, Major League Baseball players and the population of Chad to his list of enemies – he faces at least one fight not of his choosing. Robert Mueller, the special counsel appointed to investigate Russian links to Trump’s presidential campaign, has been unearthing documents and interviewing witnesses since May, and could issue a felony indictment against one or more of the president’s associates at any moment.

Trump’s instinctive reaction when faced with sudden threats is to point furiously elsewhere, and nothing could more effectively eclipse serious allegations of criminality than a nuclear first strike; it would be a holocaustic distraction like no other. The doomsday scenario is a lot less fantastic than it ought to be. Oversight isn’t much valued in the White House these days, but some people can still tug at Trump’s sleeve. Let’s hope they’re paying attention.