Trump tariff threats are bad, but the uncertainty they instil is much worse

Firms tend to hold back from investment when they are unsure what the policy landscape will look like – as the UK learned during several years of Brexit wrangling. Photograph: Dado Ruvić/Reuters

Donald Trump’s latest tariff threat, in pursuit of his goal of seizing Greenland, is a political nightmare for European leaders, but it could create a severe economic headache too.

As the International Monetary Fund (IMF) has repeatedly pointed out since Trump’s trade war began in earnest last year, whatever the ultimate level of tariffs, uncertainty takes its own toll.