For some, it will always be 1939. We are forever telling ourselves how, in the 1930s, the US and Britain underestimated the threat from Germany and Japan, how Winston Churchill alone among western leaders saw the danger and summoned his country to a defence of democracy against the Nazis. The 70 years of American leadership following the second world war were a catalogue of Churchillian moments, from the Berlin airlift to the fall of the Berlin Wall.

There is much truth to this: the US and its allies performed admirably in creating a peaceful and liberal international postwar order in Europe and Asia. But this narrative is highly selective. There were many moments when western leaders believed they were Churchill: the UK’s Anthony Eden in the 1956 Suez crisis, US Presidents Lyndon Johnson in Vietnam and George W Bush in Iraq. They overestimated the threat they faced and made things worse, provoking unnecessary and counterproductive wars, while undermining political support for an internationalist foreign policy.

The focus of today’s debate ought to be: how should we prioritise the threats facing us and how bad are the most serious? This year we have seen a fast-moving sequence of events, from Russia’s annexation of Crimea to China’s assertion of sovereignty over the South and East China seas to the collapse of the Iraqi government’s power. Authoritarian forces are on the move.