The first foreign policy priority of the next American president will be to work out how to avoid direct conflict with China or Russia. Both countries, in different ways, challenge US dominance. War between the great powers is once again a possibility. For better or worse, we are returning to a world of great power balance.

China’s economy is, in purchasing power terms, comparable to America’s. Its military has invested in the means to counter US power and is exercising it in the East and South China Seas. President Xi Jinping has cast aside Deng Xiaoping’s “hide and bide” strategy and demands influence commensurate with China’s power. In doing so, he is rubbing up against the US and its Asian allies.

Since 2000, Russia has put the proceeds of a high oil price into military modernisation. Economically, it is not a great power but it has a full spectrum of military capability to ensure its own security and rebuild a sphere of influence beyond its borders. Russia has gained from being assertive, in Ukraine and Syria and in the cyber domain, whetting President Vladimir Putin’s appetite for challenging America. The “post-truth world” in the west — exemplified by Donald Trump’s casual way with facts in the US presidential campaign — is also a gift to Russia’s formidable propaganda machine.