For other countries the nominal exchange rate may matter because changes in the nominal rate also lead to (partially or wholly temporary) changes in the real exchange rate and thus in net exports, which are targets of policy.
Interest rate and/or fiscal policy can be used to try to affect the exchange rate; for instance the Taylor Rule for a central bank that is also targeting the exchange rate can include an additional term in which the interest rate responds to deviations of the real exchange rate from its target level.