A Japanese newspaper reports that Japan’s government and central bank secretly intervened in the foreign exchange market last fall.

The Asahi Shimbun said Tuesday that Japan sold about one trillion yen during the first four days of November to halt the appreciation of its currency.

This marks the first time Japan has conducted a “stealth” intervention in the foreign exchange market since 2004.

Japanese Finance Minister Jun Azumi said Tokyo intervened in the foreign exchange market on October 31st last year to put the brakes on the rising yen, but the move was highly publicized.

The Japanese government released no announcement ahead of the stealth intervention in early November.