Question

How can a country intervene to keep its currency from appreciating? Why would a country want to do this?

Answer 1

The currency of the nation will appreciate when the demand for the local currency is increasing, this will also increase the flow of foreign currency in the market.

to keep the currency from appreciating in the market the nation will have to increase the supply of local currency and decrease the inflow of the foreign currency, the Fed or the central bank in the market will buy foreign currency using its local currency, this will depreciate the local currency. The nation do this to increase the exports and reduce the imports in the nation and affect the balance of trade.