Whether foreign exchange depreciates depends on the currency used in foreign exchange reserves. For example, in general countries, the US dollar is the main currency of foreign exchange reserves, so the depreciation of foreign exchange reserves becomes the problem of maintaining the value of the US dollar.

Because the United States has long pursued a strong dollar policy, the dollar will not depreciate for a long time. However, if there is a war and the war is initiated by the United States, the dollar will appreciate. For example, during the famous war in Bosnia and Herzegovina, investors worried that the war would hit the European economy, selling euros to buy dollars to hedge, and the dollar appreciated sharply against the euro. If the United States is attacked, the dollar will depreciate sharply. For example, in the famous 9 1 1 incident, the US dollar fell by nearly 10% against the Swiss franc in a few days.