why the U.S. stepped in

Key Points:

• The recent coordinated intervention by the U.S. and Japan to support the yen marks the first joint operation since 1998, driven by concerns over the yen's sharp decline and the potential destabilization of U.S. Treasury markets due to Japan's large holdings of U.S. debt.
• Washington's involvement aims to prevent Japan from having to sell large quantities of Treasuries to finance intervention, with emphasis on using the Federal Reserve's FIMA repo facility to provide dollar liquidity without forced Treasury sales.
• The intervention reflects broader U.S. economic and geopolitical priorities, including addressing what it sees as an undervalued yen that gives Japan an unfair trade advantage, and signaling strengthened U.S.-Japan cooperation amid regional tensions with China.
• Analysts note that U.S. participation enhances the intervention's credibility and deterrence against speculative attacks on the yen, but caution that without structural changes in Japan's fiscal and monetary policies, such efforts may only provide temporary relief.
• Some experts criticized the intervention mechanics, particularly the U.S. selling euros rather than dollars to buy yen, arguing this could confuse markets and diminish the effectiveness of the operation, while highlighting that yen depreciation is fundamentally linked to Japan's bond market policies.