Japan is preparing to publicly confirm that it coordinated with Washington to prop up the yen, according to two government officials who spoke on condition of anonymity. Finance Minister Satsuki Katayama is expected to make the announcement on Monday, marking the first joint currency intervention between the two allies in roughly 15 years. Main Developments The announcement, expected Monday, will detail what officials describe as a joint effort to arrest the yen’s slide to its weakest levels since 1986. One source familiar with the matter said the operation is “still ongoing,” indicating that further intervention may occur if needed. Market sources told Reuters that Japanese authorities bought yen in New York trading hours on Thursday, with Bank of Japan data suggesting the intervention involved as much as $58.97 billion. Another suspected round of yen-buying followed on Friday, shortly after BOJ Governor Kazuo Ueda held a press conference, causing the currency to spike. Read also: Inside Pakistan's plan to end fuel hoarding with digital tracking Coordinating with Tokyo, the U.S. Treasury reportedly informed several banks on Friday that it might intervene in the yen market and advised them to “stand ready for future action,” according to a source familiar with the matter. Treasury Secretary Scott Bessent, who recently described the yen as “very undervalued,” was photographed at a cabinet meeting with a notepad reading “Buy Japanese Yen (JPY) $5-10 bil.” Background The intervention follows a prolonged period of yen weakness driven by a widening interest-rate differential between Japan and the United States. The Federal Reserve’s shift toward a more hawkish stance has strengthened the dollar against the yen, while the BOJ has only recently signaled a potential rate hike. Tokyo’s initial intervention on Thursday came hours before the BOJ decided to keep monetary policy unchanged, though it hinted at a strong possibility of raising rates soon. Top currency diplomat Atsushi Mimura said the Ministry of Finance would respond “in close coordination with monetary policy,” underscoring the synchronized approach. This is the first joint yen intervention since 2011, when the two nations cooperated to counter currency speculation following the earthquake and tsunami. The rare collaboration highlights the severity of the current currency crisis. Why It Matters The joint action signals a significant escalation in efforts to stabilize the yen, but it also raises concerns about the broader economic implications. Critics have noted that Japan’s ability to sustain yen-buying intervention could be constrained, as selling its massive U.S. Treasury holdings to fund such operations might trigger a selloff in U.S. debt and push yields higher. Washington’s involvement appears driven by its own worries about rising Treasury yields, which could worsen if Tokyo failed to prevent a selloff in yen and Japanese government bonds. Former BOJ official Nobuyasu Atago observed that both nations face risks of inflation turning hot, leaving their central banks behind the curve—hence the mutual interest in cooperation. On the domestic front, Japan is also grappling with rising JGB yields, prompting Economy Minister Minoru Kiuchi to pledge enhanced communication with markets to maintain trust in the country’s fiscal sustainability. What's Next Katayama’s Monday announcement is expected to formalize the joint intervention and outline the two governments’ commitment to combat what they view as excessive yen declines. The ongoing nature of the operation suggests further action could be taken if market conditions warrant. Attention will also turn to the BOJ’s next policy meeting, with markets anticipating a possible rate hike in the near term. The coordination between the Ministry of Finance, the central bank, and the U.S. Treasury will be closely watched for signs of sustained intervention or new measures to address currency volatility.