What happens when an unstoppable force meets an immovable object? For 80 years in global foreign policy we never had to answer this question. America was the unstoppable force, and the order the United States built of open trade and global alliances was treated as the immovable object. But that restraint is over.

Survey the last year or so from a European seat for evidence. An American president declared his intention to acquire Greenland, considering even taking it by force. When other allies sent units to stand with Denmark against its own ally, Trump threatened to tariff them instead. He struck Iran’s nuclear sites, and then, having already cut off Ukraine’s military aid, asked Kyiv to help defend American bases in the Gulf against Iranian drones. He drove tariffs on friends and adversaries alike to their highest level in a century, before embracing a dance a Financial Times journalist would dub Taco: “Trump Always Chickens Out.”

Let’s call this the Trumpian Strategic Chaos. The strategy, insofar as it could be called one, is unpredictability itself. Allies and adversaries are interchangeably treated as malign, and every prior commitment is merely provisional, depending on the current mood.

The danger with such a strategy is not that America has turned coherently hostile, because adversarialism at least keeps everyone in character (every play needs a villain, and knowing who this is allows you to at least plan your enemy lines). Unreadability is the more nefarious aspect of the Trumpian era. You cannot build a supply chain or a 30-year defence plan around a coin flip – which is exactly why Taco threatens to paralyse the global economy. Chaos........

© The Irish Times