Japan's top currency diplomat Masato Kanda, who will instruct the BOJ to intervene, when he judges it necessary, warned that recent movements in the foreign exchange market have been rapid, and authorities stand ready to take steps in the market if needed, per Bloomberg. 

Key quotes

“Recent Yen moves are rapid.”

“Closely watching FX moves with a high sense of urgency.”

“Will take appropriate actions if needed on forex.”

“Ready to take action on forex anytime 24 hours all year around just like natural disaster.”

“Rapid forex moves could have adverse impact on economy.”

“Closely communicating with the Bank of Japan.”

“Up to the BOJ to decide monetary policy.”

“FX moves seem to be reflecting both fundamentals and speculative moves.”

“We perceive the Yen's fall by around 10 Yen a month as rapid.”

“Suggests appropriate responses to weak yen could include intervention