The yen came under severe pressure in July 2026, falling to ¥163.99 against the dollar, its weakest level in roughly four decades, as a wide US-Japan interest-rate gap encouraged yen-funded carry trades while elevated energy prices increased Japan’s demand for dollars to pay for imported fuel. The combination left Tokyo confronting both a financial-market problem and a rising import bill:
the weaker the yen became, the more expensive its dollar-priced energy purchases became in local-currency terms.
Japanese authorities moved to arrest the decline, and the United States subsequently joined Tokyo in an unusual coordinated intervention. Washington reportedly sold euros rather than dollars to buy yen, while Japan had access to a Federal Reserve mechanism that could provide dollar liquidity against US Treasury collateral rather than requiring those securities to be sold outright.
That structure helps explain why the episode mattered beyond the foreign-exchange market. Japan is the largest foreign holder of US Treasury securities, with about $1.143tn, and held $1.287tn in official reserves at the end of June, including almost $929bn in foreign securities, according to its Ministry of Finance. A prolonged defence of the yen financed through sales of dollar assets could therefore, under stressed conditions, transmit pressure from Japan’s currency market into US government debt.
There is no evidence that Tokyo was preparing a large-scale liquidation of Treasuries, nor that Washington’s support represented a bargain to prevent such sales. The significance is instead structural: prolonged intervention could have required Japan to mobilise more of its dollar assets, while the US had an interest in avoiding unnecessary disruption to the Treasury market.
What began as a Japanese currency problem had therefore become a wider test of the financial links connecting the yen, dollar, euro, US Treasuries and global energy markets — and of how far Washington was prepared to use the architecture of the dollar system to contain the pressure.
The Trade Behind the Yen’s Fall
At the centre of the currency pressure was the persistent gap between US and Japanese interest rates.
That differential encouraged the yen carry trade: investors borrowed cheaply in yen, converted the proceeds into dollars and invested in higher-yielding assets. The resulting yen sales could become self-reinforcing as expectations of further depreciation attracted additional positions.
Higher energy prices compounded the problem. Japan is a resource-poor economy heavily dependent on imported crude oil, LNG and other fuels, much of which must ultimately be financed in dollars. Rising oil prices therefore increased the foreign currency required by Japanese importers at the same time that financial flows were already favouring the dollar.
Japan was consequently being squeezed through two channels: the financial-market effect of the US-Japan interest-rate differential and the real-economy effect of a higher dollar-denominated energy import bill.
The combination intensified imported inflation and increased pressure on the Bank of Japan to continue normalising monetary policy.
Why Washington Had Something to Lose
Japan can support the yen by selling dollar assets and using the proceeds to buy its own currency. Given the scale of Tokyo’s reserves, how that intervention is financed matters beyond Japan.
If substantial quantities of Treasuries were sold, additional supply could depress bond prices and put upward pressure on US yields. Those yields influence borrowing costs across the American economy, from mortgages and corporate debt to the federal government’s own financing.
Japan’s Treasury portfolio should not, however, be regarded as a financial weapon. Disorderly liquidation could also reduce the value of Tokyo’s remaining holdings and disrupt markets in which Japanese financial institutions have substantial exposure.
The issue was therefore one of financial transmission rather than leverage: a prolonged currency defence could potentially turn pressure on the yen into pressure on US government debt.
Turning Treasuries Into Dollar Liquidity
The Federal Reserve’s Foreign and International Monetary Authorities Repo Facility, or FIMA, provides an alternative to outright Treasury sales.
It allows eligible foreign monetary authorities to obtain dollars against US Treasury securities:
Treasury sale: securities → dollars → yen purchases
FIMA: Treasury collateral → dollar liquidity → yen purchases
The second route can provide intervention funding while limiting additional Treasury supply in the market.
US Treasury Secretary Scott Bessent welcomed Japan’s intended use of the facility and suggested the Federal Reserve could consider increasing its capacity, describing mechanisms such as FIMA as safeguards against overseas financial instability spilling into the US economy.
FIMA therefore addresses an important balance-sheet problem: Japan can potentially obtain dollar liquidity while retaining the Treasuries themselves, reducing the risk that currency intervention generates unnecessary stress in the US bond market.
Why Washington Used Euros
The US contribution addressed a different side of the transaction.
Rather than selling dollars to buy yen, Washington reportedly sold euros from its foreign-exchange reserves and purchased the Japanese currency. The effect was to support the yen without directly increasing the supply of dollars in FX markets.
The US could do this because its official reserves include euros and yen. Washington was selling currency it already owned, not European Central Bank assets.
The two mechanisms therefore served different purposes: FIMA could reduce Japan’s potential need to sell Treasuries, while the euro-funded US intervention supported the yen without directly selling dollars.
The euro nevertheless introduced a third currency into what was principally a US-Japanese operation. The ECB was reportedly caught off guard by Washington’s euro sales. Although the US did not require European permission to sell its own reserves, the episode demonstrated how intervention intended to stabilise one currency can transmit effects elsewhere in the international monetary system.
Why the UAE Didn’t Get the Same Treatment
The UAE provides a useful counterexample to the idea that large holdings of US assets alone determine access to Washington’s monetary support.
Abu Dhabi reportedly explored a US dollar-liquidity backstop as regional instability raised concerns over potential pressure on the dirham’s dollar peg. Its circumstances, however, differed fundamentally from Japan’s.
The yen is freely floating and has suffered sharp market-driven depreciation intertwined with carry trades. The dirham, by contrast, is pegged at about Dh3.6725 to the dollar, and the UAE was seeking precautionary dollar liquidity rather than asking Washington to reverse a comparable currency collapse.
There is also an institutional distinction: Japan is part of the Federal Reserve’s small network of permanent central-bank dollar swap arrangements; the UAE is not.
The different responses therefore reflected exchange-rate regimes, dollar-funding requirements and positions within the international financial architecture — not simply Treasury ownership. Holding substantial US government securities may affect Washington’s assessment of contagion risk, but it does not automatically confer access to US currency intervention or permanent Federal Reserve liquidity.
US Jobs Data Changes the Equation
The market dynamic shifted again on August 7 when unexpectedly weak US employment figures showed the economy lost 23,000 non-farm payroll jobs in July, against expectations for an increase of about 80,000.
The dollar fell as much as 1.1 percent against the yen to ¥156.68, taking some of the pressure off the Japanese currency.
Unlike direct intervention, weaker US data affected one of the fundamental forces behind yen weakness. Lower Treasury yields and softer expectations for Federal Reserve policy narrowed the prospective US-Japan interest-rate differential, reducing the attraction of yen-funded carry trades.
A sustained narrowing of that gap could prove more durable than intervention because it changes the economics underlying the trade itself.
What Markets Watch Next
Whether the yen’s recovery holds may therefore depend increasingly on the direction of interest rates and energy prices.
If weaker US economic data pushes Treasury yields lower while the Bank of Japan continues gradually tightening policy, the yield advantage underpinning yen-funded carry trades should narrow further. Renewed strength in US growth or inflation could reverse that process and put the yen under pressure again.
Oil provides the second variable. Another energy-price surge would increase Japan’s dollar import requirements and amplify the inflationary consequences of currency weakness. Falling oil prices would ease both pressures.
That leaves US inflation and employment, Federal Reserve policy, Bank of Japan decisions and global oil prices as the principal tests for the durability of the yen’s recovery.
Japan nevertheless faces a difficult balance: tightening too slowly risks renewed currency pressure, while moving too aggressively could add stress to its highly indebted economy and domestic bond market.
From a Yen Crisis to a Global Currency Question
Japan’s experience raises a broader question, but the distinction between the causes of the crisis and the architecture through which it spread is important.The yen’s immediate problem was principally the wide US-Japan interest-rate differential, which encouraged yen-funded carry trades and capital flows towards higher-yielding dollar assets. The surge in oil and energy prices associated with the Iran conflict added a second pressure: as a heavily energy-import-dependent economy, Japan needed more dollars to pay a rising fuel bill just as its currency was weakening.The international monetary system did not create those shocks. But its concentration around the dollar helped connect and amplify them. Higher US rates strengthened the attraction of dollar assets; higher oil prices increased Japan’s need for dollars; yen weakness made those imports more expensive; and defending the currency raised questions over how Japan might mobilise its enormous stock of dollar reserves and US Treasuries.What began with interest rates and energy prices therefore ultimately drew in the yen, dollar, euro, US Treasuries and central-bank liquidity facilities.That chain raises a legitimate question about whether greater monetary diversification could provide economies with additional shock absorbers. A more multi-currency architecture for reserves, trade settlement and some international pricing would not have prevented Japan’s interest-rate imbalance or the oil-price shock. Nor would it eliminate exchange-rate volatility. But it could reduce the extent to which several independent shocks are forced through the same currency and financial channel.For energy-importing economies, that distinction matters. When commodities are predominantly dollar-priced, reserves are heavily dollar-based and international financing is concentrated in dollars, a rise in US interest rates can coincide with a stronger settlement currency and a more expensive energy bill. Separate economic shocks can consequently reinforce one another.The dollar’s dominance nevertheless reflects substantial advantages: deep liquidity, efficient hedging markets, global banking networks and the unparalleled scale and accessibility of the US Treasury market. Replacing the dollar with another dominant currency would therefore neither be straightforward nor solve the underlying concentration problem.The more consequential question is whether the international monetary system can gradually become more genuinely multi-currency, allowing the dollar to remain its principal currency while deeper euro, renminbi, yen and other markets — potentially alongside basket-based settlement or reserve instruments — provide additional diversification.Japan’s crisis was caused primarily by an adverse interest-rate differential and compounded by an energy-price shock. But the way those pressures travelled through the dollar, Treasuries, euro and central-bank liquidity system exposed a broader vulnerability: when too many parts of global finance depend on the same monetary channel, a policy decision in one economy and a commodity shock elsewhere can converge into a much larger problem for another. The case for greater currency diversification is therefore not that it would prevent such shocks, but that it could help prevent all of them from travelling through — and reinforcing one another within — the same financial pipeline.
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