As President Barack Obama begins a tour of Asian capitals, the standard assumption in the west is that his meetings will be with leaders of nations that rank as America's junior partners. Yet the reality is more complex. Amid the rubble of the financial crisis, the US position as singular superpower and global economic top dog looks increasingly under threat.

In particular, when he reaches Beijing next week, nothing will be able to disguise the fact that Mr Obama is paying a visit to his country's biggest creditor.

Those who take pleasure in America's discomfort point out that this global economic colossus has become shackled to the world's largest pile of international debt and pulled down by a sinking currency. By common consent China is the chief beneficiary of the financial debacle and a serious challenger to US hegemony.