A few months ago Tim Geithner, the US Treasury secretary, assured a group of Chinese students in Beijing that their country’s US dollar investments were in good hands. “Chinese assets are very safe,” Mr Geithner said. His comments brought the house down.

White House officials will be hoping that Barack Obama can avoid a similar loss of face on Monday when he meets a group of students in Shanghai for the set piece “town hall” that has become the US president’s signature event.