Per CNA, the US and Japan intervened last week, lifting the yen from a 164 low to 155.23, with analysts calling a September BOJ hike near-certain.
Why Did the US and Japan Jointly Intervene in the Yen Market?
According to CNA, the United States and Japan spent months preparing before jointly countering speculative bets against the yen last week, taking what CNA describes as a "rare unified stance" on a currency issue [E1]. The Liberty Times (LTN) reports the two countries intervened jointly "to curb excessive yen volatility and disorderly moves, and to prevent the yen from moving further toward its 40-year low" [E9]. That low — roughly 164 yen per dollar — was set in July 2026 [E11], giving the intervention a concrete reference point to push back from.
How Did the Yen Move After the Intervention?
LTN reports that in Tokyo morning trading on August 3, the yen rose to 155.23 per dollar, its strongest level in roughly three months [E10]. By August 4, the yen had eased 0.3% to 157.54 per dollar — still well off the July 40-year low of about 164 [E10, E11].
| Date | Event | USD/JPY |
|---|
| July 2026 | 40-year low | ~164 [E11] |
| Aug 3, 2026 | ~3-month high (Tokyo morning) | 155.23 [E10] |
| Aug 4, 2026 | Eased 0.3% from Aug 3 | 157.54 [E10] |
How Is the US Backing Japan's Currency and Monetary Policy?
US Treasury Secretary Scott Bessent (貝森特) posted on X on August 2 that "we strongly support Japan taking decisive market and monetary action to correct the yen's significant undervaluation," while also voicing support for a BOJ rate hike — a statement carried by both CNA [E3] and LTN [E14]. CNA further reports that Bessent said in a separate X post that he will meet Bank of Japan (BOJ) Governor Kazuo Ueda (植田和男) at the Group of 20 (G20) finance ministers' meeting the US is hosting in late August, ahead of the BOJ's next policy meeting on September 17-18 — a meeting CNA says the market views as potentially decisive [E5].
How Is Japan Aligning FX Policy With BOJ Monetary Policy?
CNA reports that Japan's Vice Minister of Finance for International Affairs, Mimura Jun (三村淳), said the government would keep its foreign-exchange policy consistent with the BOJ's monetary policy to address yen weakness, which CNA characterizes as hinting at a near-term rate hike [E4]. Separately, LTN reports that BOJ Governor Ueda said in prepared remarks that vigilance against the risk of rising prices is needed "more than ever" [E12].
Why Do Analysts See a September Hike as Nearly Locked In?
CNA reports that analysts widely expect a BOJ rate hike in September is all but decided [E2]. The chief bond strategist at Mitsubishi UFJ Morgan Stanley Securities (六浦直美) told CNA: "I feel a September hike is a done deal — if the BOJ waits until October, it would only trigger a fresh round of yen selling for nothing" [E6]. That timeline lines up with the BOJ's September 17-18 policy meeting flagged by Bessent [E5].
Are Analysts Uniformly Optimistic on the Yen's Outlook?
Not entirely. CNA cites UBS strategists (陳得能, 施奈德), who said Japan's policy mix "is unlikely to sustain yen strength," arguing that with the BOJ expected to normalize policy only gradually and real interest rates staying negative, the yen's support "comes mainly from intervention risk, rather than an improvement in domestic monetary fundamentals" [E7]. CNA also quotes HSBC as saying it lacks confidence in a sustained USD/JPY downtrend "unless the BOJ significantly accelerates its pace of rate hikes, the government takes a clearer stance on the yen, and fiscal expansion targets are scaled back" [E8].
What Happens If the Yen Weakens Again?
LTN reports that former BOJ official Atsushi Takeuchi (竹內淳) said that if the yen shows renewed signs of weakening, Japan and the US "will certainly intervene jointly again," because after becoming deeply involved in Japan's currency action, allowing the yen to slide back would put US credibility at risk [E13].
What This Means
The numbers show the intervention narrowed, but did not close, the gap with the July 40-year low: the yen moved from about 164 to a 155.23 high on August 3, then eased back to 157.54 by August 4 [E10, E11]. That partial retracement sits alongside a split in how analysts read the road ahead — CNA's sources treat a September 17-18 BOJ hike as essentially settled [E2, E5, E6], while UBS and HSBC, also cited by CNA, say the yen's recent strength rests more on intervention risk than on a durable shift in monetary fundamentals [E7, E8]. Takeuchi's warning that Japan and the US would intervene again if the yen weakens [E13] suggests officials themselves are not treating the August action as a one-time fix, which is consistent with the skepticism expressed by UBS and HSBC rather than the more confident tone from CNA's rate-hike sources.