Last week, the US joined forces with Japan to try to stop the yen’s slide. It’s the first time the two sides have intervened in the Japanese currency in 15 years, and in many ways it was an unprecedented and unusual move, with Treasury Secretary Scott Bessent choosing to sell euros (as opposed to dollars) and the use of a little-known Federal Reserve repo facility. So why did the yen’s value drop so precipitously in the first place? And will this intervention be enough to stop it? Brad Setser, senior fellow at the Council on Foreign Relations, explains why the Bank of Japan initially refrained from raising rates, why East Asian currencies (not just the yen) have been so weak lately, the improving fiscal outlook for Japan, and what to look out for next.