Japan's Impossible Position: The Yen, the BoJ, and a War It Didn't Start

Japan did not start the war in the Middle East. It has no stake in the nuclear negotiations, no seat at the table in the US-Iran talks, and no meaningful influence over whether the Strait of Hormuz opens or closes on any given morning. And yet, of all the major economies caught in the geopolitical turbulence of the past seven weeks, Japan may be the one for which the situation is most structurally damaging, and the one whose central bank faces the hardest choice.

The yen has had a miserable April. USD/JPY surged to a weekly high of 159.86 on 14 April as oil prices climbed above $105 a barrel and the safe-haven dollar found renewed demand after weekend ceasefire talks collapsed.¹ The pair briefly pulled back to 158.27 on 16 April following the G7 finance ministers' meeting, where Japan's Finance Minister Satsuki Katayama told counterparts that Tokyo was monitoring exchange rates with a "high sense of urgency" and had coordinated closely with US Treasury Secretary Scott Bessent.² But the yen buying did not last. By Friday, USD/JPY had climbed back into the upper 158 range. As of writing, the 160 level sits less than 2 yen away, a threshold that has historically triggered direct intervention.

What makes Japan's position so uncomfortable is the feedback loop between the two forces that are moving against it simultaneously. The energy shock from the partial closure of the Strait of Hormuz is pushing up import costs, since Japan is a major energy importer with almost no domestic oil production. That import-cost inflation feeds directly into consumer prices. Governor Kazuo Ueda himself warned this week that Japan is facing upside inflation risks from what he called a "negative supply shock," which is, in his words, harder to address with monetary policy than inflation driven by strong demand.³ At the same time, the same oil shock is dampening growth by worsening Japan's terms of trade, reducing real household incomes, and weighing on the corporate outlook. Inflation going up and growth going down: textbook stagflation.

The policy dilemma this creates for the Bank of Japan is almost elegant in its cruelty. The orthodox response to a weakening currency is to raise interest rates, which makes yen-denominated assets more attractive and draws capital back in. Japan has, in fact, been raising rates, with the BoJ hiking by 25 basis points to 0.75% in December 2025, its highest level since 1995. Following this, markets had been building expectations for a follow-up move.⁴ But Ueda's press conference on 17 April provided no such signal. He acknowledged the stagflationary environment rather than leaning into hawkishness, and OIS markets took the message: the implied probability of a hike at the April 27–28 meeting has now collapsed to under 20%.⁵

"By delaying the timing of the next rate hike, the BoJ is increasing pressure on the government to support the yen in the near-term."

MUFG Research, FX Daily Snapshot, 16 April 2026.²

The problem is that inaction on rates is itself a policy choice, and it is one that makes the currency weakness worse. Real interest rates in Japan remain deeply negative; the BoJ itself acknowledges that accommodation remains significant even after the December hike. Meanwhile, the Fed is on hold at 3.50–3.75%, having already trimmed 75 basis points through 2025.⁶ That differential keeps the yen carry trade alive. Investors borrow in yen at near-zero real cost, deploy the proceeds into dollar or euro assets, and pocket the spread. Every week the BoJ delays a hike without the ceasefire fully restoring the growth outlook is another week that carry positioning reasserts itself and the yen drifts lower.

The Intervention Question

The comparison that keeps surfacing in Tokyo currency desks is 2022 and 2024, when the Ministry of Finance authorised direct yen-buying operations after USD/JPY breached levels judged to be disorderly. Those interventions worked in the short run: the yen strengthened sharply in the hours after each operation. But without a change in the underlying rate differential, the effect faded within weeks.

This time, there is one meaningful difference. Finance Minister Katayama's comments at the G7 meetings this week suggested that Japan had discussed the FX situation bilaterally with the US Treasury, not just raised it in a communiqué.² Coordinated or even US-acquiescent intervention would carry considerably more market impact than unilateral action from Tokyo. Whether Bessent would greenlight such a move, given that a stronger yen also means a weaker dollar, which fits the broader preference of the current administration, is an open question. What is clear is that Japan is getting closer to the point where talking about intervention gives way to doing it.

For the BoJ, the clock is running. If the ceasefire holds and oil retreats further, the stagflation bind eases and the case for a June or July rate hike rebuilds. MUFG's economists noted this week that a failure to hike in April, combined with Katayama's remarks discouraging the central bank from moving, risks casting doubt on whether tightening is coming in June either, which would push JGB long-end yields higher as markets price a central bank falling behind the curve.⁵ That is a second-order problem the BoJ will want to avoid.

What the Yen Is Actually Telling You

Currency markets are often described as forward-looking, and the yen's persistent weakness against not just the dollar, but also the euro and even the Australian dollar, where rate hikes are already underway demonstrates something worth taking seriously.¹ It is not simply a reflection of where interest rates are today. It also reflects uncertainty about where Japan's policy normalisation goes from here, and how much the Iran shock has complicated the sequencing.

Before the war, the working assumption was that the BoJ would hike twice in 2026, taking the policy rate toward 1%, and that this gradual tightening would allow the yen to recover over the course of the year as the rate differential with the US narrowed. ABN AMRO's FX team, for instance, had argued that the narrowing of US-Japan yield spreads would be a primary yen tailwind in 2026.⁷ That story has not been abandoned, but it has been pushed back. Every meeting where the BoJ holds and the Fed also holds means the differential stays wide for longer than the market prices.

The yen is not in freefall. At 158 to the dollar, it is weaker than Tokyo would like, but not in the territory that forces an emergency response. If the Iran ceasefire stabilises and oil prices continue to fall, as demonstrated by WTI trading near $93.90 this week, down significantly from its intra-conflict highs, then the import-cost pressure eases, inflation expectations moderate, and the BoJ regains room to hike later in the second quarter. That is still the base case for most desks.

But the base case is more contingent than it was a month ago, and the yen is carrying that contingency in every daily close. Japan is bearing an economic cost for a conflict it had no hand in creating, navigating a policy dilemma that orthodox frameworks were not designed for, and watching an exchange rate inch toward a line it would prefer not to cross. The April 28 meeting will not resolve any of this. What it will do is tell markets whether the BoJ is willing to look past the noise, or whether the noise has become the story.

Footnotes

1. MUFG Research, "JPY Weekly — 20 April 2026," 20 April 2026↗ (opens in a new tab). ↩ ↩²

2. MUFG Research, "FX Daily Snapshot — 16 April 2026," 16 April 2026↗ (opens in a new tab). ↩ ↩² ↩³

3. FXStreet, "Japanese Yen underperforms as BoJ's Ueda warns of stagflation risks," 17 April 2026↗ (opens in a new tab). ↩

4. CNBC, "Bank of Japan raises benchmark rates to highest in 30 years," 19 December 2025↗ (opens in a new tab). ↩

5. MUFG Research, "Japan Economic and Financial Weekly — 20 April 2026," 20 April 2026↗ (opens in a new tab). ↩ ↩²

6. OANDA MarketPulse, "2026 FX Outlook: Improved global growth boosts weaker US dollar," 29 December 2025↗ (opens in a new tab). ↩

7. ABN AMRO, "FX Outlook 2026 — More dollar weakness ahead," 2025↗ (opens in a new tab). ↩