The United States has joined Japan in a rare coordinated intervention to buy yen and support the struggling currency, with Treasury Secretary Scott Bessent pledging the Trump administration would do 'whatever it takes' to keep supporting the yen. The joint effort, the first coordinated US-Japan intervention to support the yen since 2011, comes after the Japanese currency sank to roughly 40-year lows of around ¥164 per US dollar before rebounding to about ¥156 following Friday's action. Bessent argued the yen has become 'substantially undervalued,' increasing the risk that other countries could weaken their own currencies to stay competitive, and said supporting Japan helps protect the American economy by keeping financial volatility 'offshore.' He also expressed support for expanding the Federal Reserve's Foreign and International Monetary Authorities Repo Facility, which allows major central banks to temporarily borrow dollars against their Treasury holdings instead of selling them outright, reducing potential pressure on US Treasury prices and borrowing costs.