US Treasury holdings: Japan vs China

This is based on data from the Treasury Department on Major Foreign Holders of U.S. Treasury Securities. The chart below(click to enlarge) through January 2009 shows that China passed Japan in official holdings in September 2008. Now we know from Brad Setser's analyses that there is more than just official Treasury holdings to consider when comparing total foreign investment of different countries. But I find it interesting that China didn't surpass Japan until very recently in terms of official UST holdings. Japan's decisions regarding its holdings will be as significant as China's in terms of the effect on the USA's fiscal policies.