Hillary Clinton revealed America’s deep anxiety over China’s growing economic power and hold on US finances by asking Australia’s then prime minister: “How do you deal toughly with your banker?”

The question, at a lunch with Kevin Rudd last March and reported in a US Department of State cable, underscores the evolving and often difficult relationship between the world’s superpower and an increasingly mighty China. It is the largest holder of US treasury bonds, with around $870bn.