Who lost China? This cry went up in the US after Mao Zedong’s victory in China’s civil war in 1949. It was a strange question. When did the US own China? Strange or not, this cry helped Republicans win power in 1952. It promoted the rise of Joseph McCarthy, whose politics had similarities to those of Donald Trump — above all, in the charge that traitors infest the US government. In the senator’s case, the target was the state department; for Mr Trump, it is the FBI. The question today is: who lost America? And is it lost for good?

Nobody of course owns the US, apart from Americans. Yet, for westerners and many others, the US stood for something so attractive that it seemed to be “ours” — the guarantor not just of its own freedom and prosperity, but that of hundreds of millions of others. My father, a refugee to the UK from pre-second-world-war Austria, had no doubt. The US was the bastion of democracy. It had saved Europe from falling to Nazi or communist dictatorships. As a journalist and documentary film-maker, he knew about its mistakes. But the US was not just any great power. It embodied the causes of democracy, freedom and the rule of law. This made him fiercely pro-American. I inherited this attitude.

In the postwar world, US policy had four attractive features: it had appealing core values; it was loyal to allies who shared those values; it believed in open and competitive markets; and it underpinned those markets with institutionalised rules. This system was always incomplete and imperfect. But it was a highly original and attractive approach to the business of running the world. For those who believe humanity must transcend its petty differences, these principles were a start.