Japan will respond appropriately to excessive volatility in the foreign exchange market, its top currency diplomat said Tuesday in a fresh warning against “speculative” and “disorderly” yen moves after market talk of interventions last week. Masato Kanda, vice finance minister for international affairs, said foreign exchange rates should be stable, reflecting economic fundamentals, a view consistently expressed by Japanese authorities who are concerned about the negative impact of rapid fluctuations on households and businesses. Still, he remained silent on whether Japan stepped into the marke…