A well-known diplomatic tool to help ease the way to an agreement is humour. It brings levity, loosens the atmosphere and makes discussion less tense. Vice-Premier Wang Yang's jokes in opening remarks at this year's US-China strategic and economic dialogue in Washington were uncharacteristic for a Chinese official, but they were just what was needed. In an instant, difficult relations gave way to laughter, putting last week's two-day talks on the right footing.

It would be simplistic to contend that Wang's unscripted jibes at gay marriage and the recently-announced divorce of American media baron Rupert Murdoch and his Chinese wife, Wendi Deng Murdoch, were the reasons for the economic and geopolitical deals struck. Humour is, after all, just one of many characteristics a good diplomat must have. Sometimes, jokes do not translate well between languages and cultures. But with each slice of wit came a broader smile on the face of US treasury secretary Jacob Lew, co-chair of the meeting with Wang.

Both men are new to their jobs and have limited diplomatic experience. China's officials do not have a reputation for straying from formal statements and protocol. But President Xi Jinping's administration has made a concerted effort to break with past practices and forge a new style and image. The pledges of co-operation and partnership he and US President Barack Obama made at their summit in California last month were ably continued at the Washington talks, also attended by State Councillor Yang Jiechi and US secretary of state John Kerry.