Almost as soon as China became a major buyer of U.S. Treasury holdings nearly two decades ago, American policymakers and pundits began fretting that they would one day sell them off rapidly — wreaking havoc on the U.S. economy in the process. The past few months have been no exception. Headlines have proclaimed that China is slashing its stock of U.S. Treasurys after data came out showing that it fell to $970 billion in July from $1.06 trillion the year before, the first time in over a deca