For Europeans there is one thing worse than too much America. Not enough America. It seems only yesterday that Washington’s friends saw George W Bush’s invasion of Iraq as a heedless demonstration of US military might. Now, allies lament Donald Trump’s abdication of global leadership in pursuit of his America-first worldview. Reckless as the US was in toppling Saddam Hussein, it would be dangerously irresponsible to abandon the world to chaos.

We have been here before. Since the foundation of the republic, US foreign policy has often looked like a pendulum swinging between a selfish isolationism, uninterested in events beyond America’s shores, and a pious interventionism rooted in American exceptionalism. 

Simplistic as it may be, this characterisation has more than a measure of truth. During the 1920s and 1930s the US threw up the ramparts and closed its eyes to Europe. At the other end of the pendulum’s arc, Bush invaded Iraq, so many Americans told themselves, in the noble cause of planting democracy across the Middle East. Neither policy served the world well — absenteeism leaving Europe open to the rise of fascism, and a war of choice plunging much of the Middle East into conflicts that are still raging nearly 20 years later.