The concept of "currency manipulation" is unusable

The United States is accusing China of manipulat ing its exchange rate to weaken it . But in reality, it is impossible to define currency manipulation . N ormally , a country determined to undervalue its exchange rate is recognised by : An abnormal external surplus; but an external surplus can have causes other than an undervaluation of the exchange rate, for example Germany's huge savings in the euro zone ; Accumulation of foreign exchange reserves, but it can be explained by a determination to prevent an appreciation of the exchange rate that is excessive and too rapid , as in China until 2013; Abnormally low interest rates relative to the growth rate; but then almost all countries (including the United States) are currently manipulating their exchange rate s ; A significant depreciation of the exchange rate, but this can be the result of private sector capital outflows, as we also have seen in China. The concept of currency manipulation is therefore very difficult to use.