The role of the Fed is also not unique since the mandate is on "foreign reserves" not "dollar reserves". This means potentially the mandate could be fulfilled by matching KH's monetary mass not only in quantity but in kind - Euro liabilities matched by Euro reserves, dollar by dollar, etc. What makes the USD special is that the internal HK liabilities are matched by USD reserves, but this need not be so.

By laying out pros and cons we risk inducing people to join the debate, and losing control of a process that only we fully understand. - Alan Greenspan