But there is a significant asymmetry between intervention for fighting appreciation and intervention for fighting depreciation. •  When you are fighting currency appreciation, you are intervening in your own currency. Your capacity to do so is, at least in theory, unlimited, quite simply because you can print your own currency.
•  But when you are fighting currency depreciation, you are intervening in a hard currency. Your capacity to intervene is, therefore, limited by the size of your forex reserves. What complicates the dilemma is that the market is aware of this.