In a policy speech reflecting strains in Sino-US relations, Robert Zoellick, US deputy secretary of state, on Wednesday night urged China to adopt democratic reforms and tackle its huge trade surpluses while evolving into a “responsible stakeholder” in the international system.

Mr Zoellick spoke frankly about the differences between the two powers, especially on the international stage, where he criticised China's “involvement with troublesome states” and its “mercantilist” attempts to “lock up” energy resources. While stressing repeatedly that the US sought co-operation, not confrontation, Mr Zoellick noted that uncertainties over how China would use its power would lead the US to “hedge” its relations.