All too often since the global financial crisis, the world economy has depended on the US to keep it going. So although America’s economy has disappointed somewhat this year, and the prospects of a big fiscal boost to growth have dissipated, it is gratifying that China, the eurozone and Japan have come in to take up the slack. Yet while the US does not have to be the only engine of growth, if America starts a major conflict over international trade it has the potential to bring the whole expansion sputtering to a halt.

The International Monetary Fund’s latest forecast update, released on Monday, sees global growth unchanged from its previous projections at a healthy 3.5 per cent this year and 3.6 per cent next, with upward revisions this year in the eurozone, China and Japan. The only large advanced economies to see their forecasts revised down for this year were the US and the UK.

In the case of the US, the downgrade involved reducing the forecast by 0.2 percentage points this year and a hefty 0.4 percentage points in 2018, a large drop from a growth rate projected now to equal only 2.1 per cent.