United States President Barack Obama's participation in yesterday's town-hall meeting with Chinese youth in Shanghai sharpened the contrast between him and his predecessors on several levels.

Strong rebukes over human rights dominated Bill Clinton's initial trip to the country. George W. Bush's first visit was highlighted by poignant accusations of currency manipulation by the country he called a "strategic rival".

Obama's tone went beyond exuding a more sophisticated finesse in addressing China - that is, striking a better balance between tough talk and sweet talk - but also a fundamentally different attitude about relations.