No relationship in the world is more important than that between the US and China – so at least runs the message the Obama administration has sent since taking office.
Despite unease in both countries about the mutual dependence that exists between them – unease stoked by the populism of hard economic times – each acknowledges that it cannot tear away from the other's grudging embrace.
That interdependence will be highlighted by the G20 summit and the meeting on its margins between Presidents Barack Obama and Hu Jintao. Already, some analysts have called for a G2, of the US and China. Although falling far short of such a model, the Obama-Hu summit highlights the degree to which each country sees co-operation with the other as essential.