The US Dollar retains the global currency crown it has worn unchallenged since the end of World War 2. That crown has only been burnished this year by rising interest rates and an economy that seems to have ditched the financial-crisis blues more convincingly than any other.

However, there are reasons to be worried even about King Greenback. For one thing, the Presidency of Donald Trump polarizes the country as no administration has in the history of the Republic. America may be stronger economically, but it is hardly at ease with itself. That makes her politics volatile, her elections hard to predict. Then comes Trump’s zeal to “level” the US trade playing field, as he puts it. This has resulted in widespread spats, not just with arch-rival China but with supposed allies such as Japan and Western Europe. It may yet lead to a full-scale trade war.

At the very least, US reliability as an ally and partner is now questioned openly in places where, not so long ago, such questions would have been heresy.

THE US DOLLAR CHAFES UNDER AN INCREASING DOMESTIC DEBT BURDEN

Then there is all that debt. For an economy doing well the US sure likes to borrow. The Treasury itself predicts that IOUs in the second half of 2018 will be flying out to an extent not seen since those dark financial crisis days – a cool $769 billion. Some current projections have the deficit topping $1 trillion next year.

So far, we’ve looked at broad reasons why the Dollar might be more vulnerable that it looks at a cursory glance. There are individual countries which might want to try to get around its global pre-eminence, and who are certainly inclined to sell. Iran, Russia and China are all chafing under escalating US sanctions. By selling US Treasuries and ploughing the proceeds into things like gold – of which Russia has recently been a big buyer – they hope to head off some of the worst effects. It increased its holdings by a massive 29 tonnes in July, the largest rise since November 2016.