US-Japan Currency Alliance Seeks to Breach 155 Yen Threshold

The US-Japan handshake on currency intervention has sent shockwaves through financial markets. The shared concern of a weak yen driving up import costs for Japan and undermining US tariff policies prompted joint action. According to international media, the possibility of US intervention was considered as early as January 2026, when the Federal Reserve Bank of New York conducted interest rate probing.

Japanese Finance Minister Satsuki Katayama spoke with her American counterpart about 10 times regarding exchange rate-related issues, including a three-and-a-half-hour discussion during his visit to Japan in May. The need for action peaked in July, when the yen hit a four-decade low despite the Bank of Japan (BoJ) raising interest rates to a 31-year high in June.

The US Treasury's semi-annual currency report reiterated warnings about excessive exchange rate volatility and pledged continued close consultation with Japan. As a result, on the evening of July 30th, Vice Minister of Finance Atsushi Mimura issued an order to buy the yen. The market test is now focusing its attention on the 155 yen to 1 USD mark.

Analysts in the Japanese currency strategy department at BofA Securities believe that this time, authorities are determined to break the 155 yen to 1 USD threshold. If they fail, the market will assume they have exhausted their policy options. Conversely, if the exchange rate remains below 155 yen to 1 USD, the market structure could change.