Enlightenment doesn’t last for ever, however, and with Mr Trump’s election Americans have chosen, as in 1920, a return to normalcy. So what does the normal solipsistic superpower do? It looks for immediate threats to the homeland and finds only one: radical Islamist terrorism. Its foreign policy becomes primarily a counterterrorism strategy. Nations are judged not by whether they are allies or nominal adversaries, democracies or autocracies, only by their willingness to fight Islamists. Mr Putin’s Russia, Abdel Fattah al-Sisi’s Egypt, Bashar al-Assad’s Syria, Israel: all are equal partners in the fight and all are rewarded with control, spheres of influence and defence against critics within and without. Most countries, by this calculus, are irrelevant.

The rest is a matter of money. Foreign policy should serve US economic interests, and where it doesn’t should be changed. Trade deals should be about making money, not strengthening the global order or providing reassurance to allies living in the shadows of great powers. The US is no longer in the reassurance business. For decades an abnormal US foreign policy has aimed at denying Russia and China spheres of interest. That made sense when upholding an order to avoid a breakdown like that of the first half of the 20th century. But a narrower reading of US interests does not require it. What interest is it of the US who exercises hegemony in east Asia and in eastern and central Europe? Existing alliances need not be re­nounced — that would be messy — but, if allies have to adjust to new realities, that is to be welcomed rather than resisted.

As for the projection of US military power abroad, there should be no need. No foreign army threatens the homeland. Nuclear powers can be deterred by America’s nuclear arsenal. (Note to US hawks: there will be no bombing of Iran under a Trump administration.) Almost every intervention of the past 70 years was primarily to defend someone else or to uphold some principle of global order. They were “wars of choice”, not required by a narrow definition of US interests. The war against radical Islamist terror can be fought by drone strikes a few special forces and by our partners on the ground.