The U.S. and Japan have jointly intervened in currency markets to prop up the Japanese yen after it sank to a fresh 40-year low, marking the first coordinated yen-buying operation since 2011.
Why it matters: A weak yen isn’t just Japan’s problem. It has implications for U.S. manufacturing, inflation and even mortgage rates.
- President Donald Trump said the U.S. was helping Japan “as a sign of friendship” and to support the global economy.
- Treasury Secretary Scott Bessent also confirmed Friday’s intervention, saying Washington “will not hesitate to participate in further joint intervention.”
The backdrop: A persistently weak yen creates several challenges for the United States. It gives Japanese exporters a pricing advantage over American manufacturers, potentially undermining Trump’s effort to bring manufacturing back to the U.S. through tariffs.
- It also raises inflation pressures in Japan by making imports more expensive. If inflation accelerates, the Bank of Japan could be forced to raise interest rates more aggressively.
- That matters because higher Japanese bond yields could encourage investors to move money out of U.S. Treasuries and back into Japanese government bonds.
$1 Trillion dollars. Japan is the largest foreign holder of U.S. government debt, owning roughly $1.14 trillion in Treasuries. If those flows reverse, Treasury yields could rise, increasing borrowing costs throughout the U.S., including mortgage rates.
The debate: Bessent argues the intervention is justified because the yen has become fundamentally undervalued. “We strongly support Japan’s decisive market and monetary steps to correct the substantial undervaluation of the yen,” he told reporters.
Not everyone agrees. Robin Brooks of the Brookings Institution argues the yen’s weakness is a symptom of a much larger problem: Japan’s massive debt burden.
- Writing on Substack, Brooks contends that the currency is falling because Japan continues to suppress government bond yields through central bank intervention. “As long as central banks intervene to artificially cap government bond yields, this transfers fiscal stress from the bond market to the currency,” Brooks wrote. “The yen isn’t overshooting.”
- He argues that if Japan allowed bond yields to trade freely, 30-year Japanese government bond yields could be at least 300 basis points higher, potentially triggering a debt crisis.
The bottom line: The coordinated intervention may provide temporary support for the yen, but it does little to resolve the underlying debate. The U.S. sees an undervalued currency that threatens global stability, while critics argue the yen’s weakness reflects Japan’s deeper fiscal challenges that currency intervention alone cannot fix.