The intervention was the first time in nearly three decades that the United States stepped in to support the yen. It would certainly be a problem for the U.S. if Japan sold its Treasury bonds. A bank or hedge fund may well hold large positions in yen, and the institution could have been in trouble if the currency’s value kept on falling. Under Bessent’s control, the Treasury Department has developed a taste for the currency market. Last year, the Treasury established a $20 billion currency swap line with Argentina when the government faced financial pressure.