A Currency Defense War in Asia: Under the Pressure of US Dollar Appreciation, Japanese and South Korean Officials Rarely Make Joint Actions. As the appreciation of the US dollar puts downward pressure on Asian currencies, South Korean and Japanese government officials made a rare joint effort on Wednesday to verbally intervene in the foreign exchange market. Japanese and South Korean officials have expressed serious concern about the recent depreciation of their own currency and emphasized their readiness to take action to address excessive exchange rate fluctuations.