In the mid 1940's, Britain was a spent force. Following the two wars, it had a huge debt problem. US helped it out, but made sure that it occupied the centre-stage thereafter.
US needs external capital to finance its bailout and many more future bailout proposals. It needs Japan and China. Can the Chinese govt say, for ex, take those ships away from East Asia, calm down on Taiwan etc.? It is at these times that the geo-political situation of the next 50 years is written. Can the Chinese exploit the situation to their advantage? I will bet they do. Chinese are far more ambitious than Japanese.