Full Breakdown
Japan’s Top Currency Diplomat Urges Markets to Heed Clear Warning on Yen Weakness
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Core Event – Mimura’s Call for Market Discipline
On September 28, Atsushi Mimura, Japan’s vice finance minister and top currency diplomat, told Reuters that “Japan’s prime minister, finance minister and the US have sent a very clear message. Markets should take that message at face value.” He said he was “neither satisfied nor reassured” by the yen’s recent moves and would watch closely whether markets heed the warning. Mimura declined to comment on any future intervention but dismissed concerns that funding constraints would limit Japan’s ability to act.
Background & Context
The yen has weakened amid a widening yield differential between Japan and the United States. The Bank of Japan raised its policy rate to a 31-year high of 1.25 % earlier this month, while the U.S. Federal Reserve continues to hike rates, keeping the gap large. A weak yen raises import costs, especially for fuel, which have surged because of the Middle-East war.
In July, Japan and the United States carried out a coordinated yen-buying intervention on July 31 to stop the currency’s slide toward 40-year lows. Mimura described that operation as the culmination of a “currency alliance” that extends to cooperation on economic security, critical minerals and global supply chains.
Timeline
- July 31 – Japan and the United States conduct coordinated yen-buying intervention.
- September 28 – Mimura delivers the “very clear” message to markets in a Reuters interview.
- September 18 – The BOJ is set to meet to consider further policy moves.
Data & Statistics
- The yen rose to around 156.75 per dollar, briefly breaking the 157 line after Mimura’s remarks.
- The BOJ’s 1.25 % policy rate is the highest in 31 years.
- The U.S. 10-year Treasury yield has climbed to the 5.22 % range, its highest level since 2007.
Official Statements & Responses
Mimura emphasized that Japan remains vigilant, stating that the government will “respond appropriately” on currencies based on discussions between Japanese and U.S. leaders and finance ministers. Finance Minister Satsuki Katayama confirmed that President Donald Trump raised concerns about yen weakness during a summit with Prime Minister Sanae Takaichi, and she and her U.S. counterpart Scott Bessent reaffirmed that the yen’s undervaluation is a matter of concern. Both sides signaled a shared determination to address the issue, though no concrete intervention plan was disclosed.
Verbatim Quotes
- “Japan's prime minister, finance minister and the US have sent a very clear message. Markets should take that message at face value,” — Atsushi Mimura
Why It Matters / Impact
A persistently weak yen inflates the cost of imported fuel and other commodities, adding pressure to Japan’s inflation outlook despite the BOJ’s rate hikes. Market participants view Mimura’s language as a step up the “escalation ladder” of verbal intervention, which historically slows but does not reverse yen weakness unless followed by actual market action. The narrowing rate-gap narrative suggests that future U.S. rate hikes could further support the dollar, keeping downward pressure on the yen unless coordinated policy steps are taken.
Conflicting Reports & Gaps
Some analysts have speculated that Japan’s fiscal expansion could fuel yen selling, but Mimura rejected criticism that Japan’s fiscal policy is “too expansionary.” No official timeline for a possible intervention was provided, leaving markets to gauge the seriousness of the “clear message” based on subsequent price action.
