US and Japan Launch Rare Joint Currency Intervention to Support Yen as It Nears 40-Year Low

The United States and Japan have carried out a rare coordinated intervention in foreign exchange markets to support the Japanese yen, marking the first confirmed joint yen-support operation between the two allies in decades. The move came after the yen weakened to around a 40-year low against the US dollar, prompting concerns over excessive market volatility and broader risks to the global financial system.

The coordinated action involved the US Treasury, operating through the Federal Reserve Bank of New York, working alongside Japanese authorities to stabilise the currency. According to reports, the intervention included the sale of foreign currencies—including euros—and the purchase of Japanese yen in an effort to strengthen the currency and calm disorderly market movements.

Japanese authorities are estimated to have spent between ¥6 trillion and ¥8.45 trillion (approximately $53 billion to $59 billion) over one or two trading days to buy yen while selling US dollars. Although the United States' participation was smaller, it was still considered significant. Internal documents cited by media reports indicated an instruction to purchase between $5 billion and $10 billion worth of Japanese yen, demonstrating direct US involvement in the operation.

Officials described the intervention as a response to "excessive volatility and disorderly movements" in the yen rather than an attempt to target a specific exchange rate. Policymakers have repeatedly stressed that interventions are intended to smooth abnormal market fluctuations rather than manipulate currency values for competitive advantage.

President Donald Trump characterised the coordinated action as a "signal of friendship" with Japan, saying a stronger and more stable yen would benefit not only Japan but also the United States and the wider global economy. His remarks underscored the strategic importance Washington places on maintaining financial stability among its closest allies.

Analysts point to another key reason behind the US decision to participate. If Japan had been forced to defend the yen on its own for an extended period, it might eventually have needed to sell large holdings of US Treasury securities to raise dollars for intervention. Such large-scale Treasury sales could have pushed up US government borrowing costs and disrupted global bond markets—an outcome Washington is keen to avoid.

By supporting the yen directly, US officials also hope to reduce the risk of a sharp and disorderly currency depreciation that could spill over into global trade, inflation, and financial markets. A rapidly weakening yen can increase market uncertainty, distort international capital flows, and create additional pressure on central banks worldwide.

The intervention also reflects an important shift in US policy. Treasury Secretary Scott Bessent confirmed that Washington and Tokyo had closely coordinated their foreign exchange actions and stated that both governments would "not hesitate" to conduct additional joint interventions if market conditions require further action.

Japan's Ministry of Finance echoed that position, saying it remains in close communication with the US Treasury and stands ready to undertake further coordinated measures should excessive volatility return to currency markets.

The intervention triggered a sharp rebound in the yen after it had fallen to its weakest level in roughly four decades. However, economists caution that the currency continues to face underlying pressure from the wide interest rate gap between the United States and Japan. Higher US interest rates continue to attract global investors toward dollar-denominated assets, while Japan's comparatively lower rates have weighed on demand for the yen.

Despite those structural challenges, financial markets now see an increased likelihood that the Bank of Japan could continue tightening monetary policy if inflation and economic conditions permit. Investors also believe that further coordinated interventions by the United States and Japan remain a realistic possibility should the yen come under renewed downward pressure.

The joint operation marks one of the most significant examples of US–Japan currency cooperation in recent decades, highlighting growing concern over exchange-rate stability and the potential global consequences of extreme currency movements. As markets continue to monitor interest rate expectations and economic developments, policymakers in both countries have signalled their willingness to act again to preserve orderly market conditions if necessary.