Following the joint currency intervention by Japan and the United States, the yen has returned to the center of market attention in recent weeks. The episode has intensified scrutiny of the Bank of Japan's upcoming policy decision, with some speculation that the coordinated intervention came with a commitment from Tokyo to pursue higher interest rates. Interventions of this kind involve authorities buying yen in the foreign-exchange market to push back against disorderly moves, and their staying power is generally tied to whether the underlying interest-rate picture that drives currency flows shifts in the same direction.

While a more hawkish BOJ could act as a driving factor in helping to defend the yen, the analysis questions whether it would be enough to turn the tide. The yen has been heavily punished by a multitude of factors since late last year, and beyond the ongoing US-Iran conflict, three of them are worth revisiting.

1. Japan's fiscal situation remains fragile

This is the core premise of the "Takaichi trade" that has been running since October of last year. Her appointment only heightened worries about Japan's fiscal predicament, and those concerns have not gone away.

Japan's debt-to-GDP ratio remains well above 200% and continues to rank as the highest among all major advanced and large economies — a burden accumulated through decades of heavy borrowing and stimulus dating back to the 1990s. That makes the country ill-equipped to withstand an aggressive tightening cycle, leaving the BOJ a very fine line to maneuver.

Higher interest rates would immediately balloon the Japanese government's cost of servicing its massive national debt, since a large share of that debt rolls over and refinances at prevailing yields over time. That means that no matter how much the BOJ talks about raising rates, its "terminal rate" — the point at which a tightening cycle is expected to stop — is arguably much lower than in other major economies such as the US or Europe, which knocks down the credibility of any aggressive tightening that could structurally underpin the yen in the big picture.

2. Japan's real interest rates are still a problem

Another troubling spot is that real interest rates in Japan — nominal rates minus inflation, the measure of the true return on holding yen assets — remain very much negative at this juncture. Even with the BOJ policy rate at 1%, or potentially pushed to 1.50% going forward, that level would still sit below underlying inflation, which the central bank argues is currently close to 2%. Negative real rates mean yen-denominated holdings lose purchasing power over time, reducing the currency's appeal to global capital.

This remains a key reason why the yen continues to struggle against all odds, even with the recent resurgence in Japanese bond yields. Currency traders do not trade only on nominal yields and rates, but on real rates as well. Unless the BOJ intends to take a very bold step to change the dynamics of the landscape, this is one pressure point that is set to stick around for quite some time.

Even though rate differentials have narrowed over the past two years, especially in the bond market, the rates argument still very much favors the US. As a result, the carry trade math is still working — albeit less effectively. The carry trade involves borrowing in low-yielding currencies such as the yen to invest in higher-yielding ones, and it stays profitable as long as the rate gap remains wide. It is also worth remembering that Japanese bond yields are not rising solely because of the inflation and BOJ outlook; the rise is largely tied to growing risks on the fiscal side, which presents another set of risks for traders and investors going in search of Japanese assets.

3. The BOJ has to deliver something that will truly surprise markets

At this stage, traders are already expecting at least one rate hike from the BOJ by year-end. Looking to June 2027, markets are also pricing in roughly 72 basis points of BOJ rate hikes, which translates into three more hikes between now and the middle of next year.

The one hike priced in for this year fits the current pace set by the BOJ — moving roughly once every half year — while the two priced for the first half of next year essentially imply a slight step up in that pace.

So even if the BOJ feels bolder, it would have to deliver at least three rate hikes across its four meetings in the first half of 2027 to truly signal that it means business. Anything short of that would, at best, simply match what markets have already priced in. At worst, a more timid approach — one the BOJ is known for — would instead put more pressure on the yen, particularly if the bank walks back from the more aggressive signaling approach seen in recent weeks.

In short, the onus and the pressure are on the BOJ to keep up more hawkish rhetoric and deliver something that will echo more strongly across broader markets. Currency traders have largely priced in what is to be expected above, and it would take a lot more to truly convince market participants of any sustained reversal momentum in the yen's trajectory. The immediate checkpoint is the bank's upcoming policy decision, followed by whether its delivery across the four meetings of the first half of 2027 goes beyond what markets have already priced.

The only real hope now for the yen and the BOJ, the analysis concludes, is that all the tough talk and narrative will eventually buy enough time for the US-Iran conflict to die down and become less of a headwind for the Japanese economy. That, it notes, has already been the game plan for at least five months — yet the war remains no closer to its end.