Yen intervention: America's long-term calculus and short-lived effect

On July 30 and 31, 2026, the United States and Japan jointly intervened in the yen, causing the currency to appreciate sharply from 164 yen per dollar to 157. Japan had intervened several times near 160 in recent years, but substantive action by the United States surprised the market. The U.S. Treasury had asked for market quotes in January 2026 without entering the market. Some commentators compared the latest intervention with the 1985 Plaza Accord because excessive yen depreciation had created international economic imbalances. Yet those imbalances also affect Europe and Canada, so why did neither participate? The causes and likely effects of the weak yen and this intervention require closer examination.

Japan's “strong” economy and weak yen

In its January 2026 consultation report, the International Monetary Fund described a tranquil picture of Japan's economy. The IMF said employment was strong, unemployment was low, the labor market was tight and wage growth was high. Nominal GDP was growing at around 4%, while real growth was slightly below 1%. Although real growth was modest, mainly because hours worked continued to decline, output was already above potential. CPI inflation had remained above the 2% target for three and a half years, with July at 2%, and the IMF believed current inflation expectations had converged with the long-term target of 2%. The Bank of Japan began leaving its ultra-loose policy in 2024. The IMF was optimistic that it could achieve a soft landing and normalize monetary policy by 2027 or 2028, fully withdrawing stimulus while inflation remained sustainably near 2%. The Bank of Japan's own official position, updated in June 2026, broadly matched that optimism, although it used more cautious language about inflation uncertainty.

The IMF report nevertheless raised a yen puzzle. It said the portion of the yen's exchange rate against the dollar that could not be explained by the U.S.–Japan interest-rate differential was becoming larger. From the start to the middle of 2025, tariffs caused foreign investors to lose confidence in U.S. assets, the dollar depreciated sharply against major currencies and the yen appreciated by nearly 9% against it. After tariff tensions eased in the second half, most currencies changed little against the dollar, but the yen kept weakening until it reached a low of 164 per dollar in July 2026. Japanese interest rates rose during this period, and the average yield on Japan's 10-year government bond reached 2.67% in June 2026, significantly narrowing the gap with the United States. Even so, the yen still depreciated and failed to deliver the appreciation implied by a carry-based model.

Before explaining why the United States intervened in the yen, it is necessary to explain the currency's “unexpected” weakness.

Japan's outward industrial capital and the weak yen

Although Japan has achieved full employment, the scope for new domestic investment is limited. In addition to the economy's advanced stage of development, a constrained labor supply — especially as weekly hours worked continue to fall — and high labor costs are important reasons. By contrast, Japanese industrial capital has invested very successfully overseas, and the profits generated each year are a major contributor to Japan's current-account surplus.

For Japanese companies, lower labor costs abroad make overseas investments more profitable, improve financial statements and provide a stronger boost to share prices, encouraging further expansion outside Japan. The author discussed the scale and growth of overseas profits at listed Japanese companies in an earlier article in the same publication. The outward flow of Japanese industrial capital is therefore a long-running trend that continues to grow; net overseas industrial investment exceeded $4 trillion in 2026. Japan runs a large current-account surplus of around 5% of GDP, which would normally imply currency appreciation. But overseas profits are not remitted home, which would create demand for yen and support its exchange rate, while domestic capital continues to leave the country to fund overseas expansion, generating depreciation pressure. The transfer of industry abroad also reduces the international competitiveness of products made in Japan. Japan is now in deficit in goods trade, while services trade has long been in deficit, adding further pressure on the yen. In the author's view, the continuing outward flow of Japanese industrial capital is the main reason for the currency's persistent weakness.

Why did the United States intervene in the yen?

The market has considered one plausible explanation. Japan's main tool for stopping yen depreciation is to sell dollars and buy yen. Obtaining those dollars, however, requires it to sell U.S. Treasury securities, which would push U.S. interest rates higher at a time when the Trump administration urgently wants lower rates. If the U.S. Treasury sells dollars and buys yen instead, there is no direct effect on Treasury yields. This explanation may still be insufficient: in January 2026, the Treasury only asked for quotes and did not actually purchase yen.

What prompted substantive U.S. intervention this time? As described above, the main force behind yen depreciation is the relocation of Japanese manufacturing overseas. The United States has been rebuilding its import supply chains since tariff tensions eased, and the outward movement of Japanese manufacturing fits that effort. Japan also took the friendliest stance toward the United States during the 2025 tariff dispute, making cooperation between the two countries natural.

Closer strategic interests between Japan and the United States give Washington a reason to help Tokyo strengthen the yen. Treasury Secretary Bessent spoke in a media interview about the alignment of U.S. and Japanese interests. He did not specify exactly how those interests aligned, but the author argues that the main reason is Japan's use of its manufacturing capabilities abroad to help the United States rebuild supply chains.

A related question is why the Japanese government does not want the yen to continue weakening beyond 160 per dollar. First, even a sustained move beyond that level would not constitute a “yen collapse.” Countries suffering a currency collapse usually experience a sudden and very large depreciation, severe capital flight, high inflation and extremely high interest rates. These developments are intertwined through money supply, import prices and a worsening balance of payments. Japan's economy, by contrast, is in what the author calls an “era of peace and stability,” so the yen's depreciation since the start of 2026 cannot be described as a currency collapse.

Political considerations are the main reason Japan's government intervenes. For domestic residents, especially groups with relatively fixed incomes such as the large population of older retirees, yen depreciation directly reduces real income, or in other words redistributes income within Japan. Politicians must consider those distributional effects when setting economic policy, and that is the government's principal motive for intervention.

Japan's inflation outlook: the risk of raising rates too slowly

Another important factor for the yen is Japan's long-term inflation problem. According to the Organisation for Economic Co-operation and Development, Japan's government-debt-to-GDP ratio was 200.8% in March 2026, down significantly from its historical peak of 219.4% in March 2021. Corporate and personal income-tax receipts have both grown considerably, reducing the fiscal deficit and therefore the increase in debt. From the perspective of the existing debt stock, interest rates are currently below nominal GDP growth, which is also pushing the debt ratio down. If rates keep rising as long-term inflation expectations increase, however, nominal interest rates could approach GDP growth and weaken that deleveraging effect. At this stage, the government has a strong incentive to keep rates low for longer and tolerate higher inflation, creating a latent risk that inflation expectations become unanchored.

In an earlier article in the same publication, the author analyzed Japan's Phillips curve in recent years and argued that inflation expectations were unstable. If inflation remains above the 2% target while the labor market stays tight for several consecutive years, an overly dovish Bank of Japan and excessively slow rate increases could allow expectations to rise above 2%. Once they become too high, controlling inflation becomes much harder, creating another source of pressure on the yen.

The outlook for the yen

The author argues that even as the U.S.–Japan interest-rate gap narrows, the continuing outward flow of Japanese industrial capital places sustained pressure on the yen. Because the movement of industrial capital reflects long-term structural forces, yen depreciation has long-run fundamental support. This joint U.S.–Japan effort to strengthen the yen is more forceful than several previous unilateral actions by Japan, but it is unlikely to change those fundamentals. Around 1985, by contrast, Japan's economic fundamentals themselves favored yen appreciation. The Plaza Accord moved with those forces, producing an immediate effect that lasted a long time. Over the longer term, U.S.–Japan cooperation to rebuild supply chains may accelerate the relocation of Japanese industry abroad and, through the mechanism described here, add further depreciation pressure.

Taken together, the U.S. intervention may reflect long-term strategic interests but is likely to have only a short-term effect. Because 160 yen per dollar is an important psychological threshold, intervention near that level may recur in the future.