米什金的《货币金融学》提到，小国货币汇率被高估时，央行对外汇市场进行干预：购买本国货币，减少外汇储备，基础货币、货币供给减少，直至最后耗尽。但“这个外汇干预不能进行冲销，因为进行冲销会导致国际储备的持续减少”。根据这些说法，貌似不进行冲销而只是出售外汇、购入本币，国际储备将不会减少？进行非冲销性干预不也同样可以耗尽外汇储备吗？冲销操作的目的是什么呢？谢谢！
原文如下：

If there  is perfect capital mobility-that is,  if  there are no barriers to  domestic res-
idents purchasing foreign  assets or foreigners purchasing domestic  assets-then  a ster-
Ilized  exchange  rate intervention cannot keep  the  exchange  rate  at  because, as we
saw earlier in  the  chapter, the relative expected return of domestic assets is unaffected.
For example ,  if the  exchange  rate is  overvalued, a sterilized purchase of domestic  cur-
rency  will leave  the  relative expected  return  and  the  demand  curve  unchanged-so
pressure for a  depreciation of  the domestic  currency is not removed. If  the central bank
keeps purchasing its  domestic currency but continues  to  sterilize, it will just  keep los-
ing  international reserves until it finally runs out of  them  and is  forced  to let  the  value
of the currency seek a lower level.

One important implication  of the  foregoing  analysis  is  that a  country that Lies
its exchange rate to an anchor  currency of  a large r country loses  control of  its mon-
etary policy.  If the larger country pursues  a  more  contractionary monetary policy
and  decreases its money  supp ly,  this  would lead  to lower expected infla tion in  the
larger  country,  thus  causing  an  appreciation  of the  larger  country' s  currency  and  a
depreciation  of  the  smaller  country' s  currency.  The  smaller  country,  having locked
in  its exchange rate  to  the  anchor  currency,  wtll now find its currency overvalued
and will therefore have to sell the  anchor currency and buy its  own to keep its cur-
rency from depreciating .  The result  of this foreign exchange intervention will then
be a  decline in  the  smaller country' s international reserves, a contraction of  its mon-
etary base, and  thus a decline in  its money  supply.  Sterilization of  this foreign exchange
intervention  is  not  an  op tion  because  this  would  just  lead  to  a  continuing  loss  of
international  reserves  until  the  smaller  country was  forced  to  devalue its  currency.