A weak yen and soaring oil prices are hitting Japan at the same time. In March 2026, with the yen inching toward the critical 160-per-dollar line, the de facto blockade of the Strait of Hormuz sent Japan's energy import costs through the roof. Gasoline hit an all-time high. With an energy self-sufficiency rate of just 13%, the Japanese economy is showing exactly how thin its margin is.

The Yen Approaching 160: What's Happening?

On March 18, 2026, the yen fell to 159.90 per dollar in New York trading, its weakest level since July 2024. The psychologically significant 160 mark is now within striking distance.

Several factors have stacked up. On February 28, the United States and Israel launched a massive military strike against Iran. Following the killing of Iran's Supreme Leader Khamenei, Iran's Islamic Revolutionary Guard Corps (IRGC) announced on March 2 that the Strait of Hormuz was closed and that ships attempting passage would be burned. The escalation triggered a classic flight to the dollar, pushing the greenback higher and the yen lower.

Making matters worse, surging oil prices are fueling expectations of a widening Japanese trade deficit. Japan imports virtually all of its energy resources, meaning higher oil prices inflate the import bill and increase "real-demand yen selling", where importers sell yen to pay for oil in foreign currencies. This creates a vicious cycle where rising oil prices and a falling yen reinforce each other.

The Bank of Japan (BOJ) has signaled a hawkish stance on monetary policy, but markets remain skeptical that tighter policy alone can stem the tide. In a survey of 15 foreign exchange specialists at major financial institutions, most identified 160 yen per dollar as the likely trigger for government intervention. However, analysts note that yen weakness driven by oil fundamentals doesn't easily meet the criteria for intervention, which typically requires "excessive" or "disorderly" currency movements driven by speculation.

The Hormuz Strait Blockade: 20% of the World's Oil Supply at Risk

The Strait of Hormuz is a narrow waterway, just 33 kilometers (20 miles) wide, connecting the Persian Gulf to the open ocean. Roughly 20 million barrels of oil per day pass through it, accounting for approximately one-fifth of global oil consumption. Around 20% of the world's liquefied natural gas (LNG) trade also transits these waters.

The strait was never physically sealed. What closed it was the insurance market. In early March, major marine insurers stopped writing war-risk cover, and without insurance no shipowner can carry the exposure. Maersk, MSC and other major lines suspended transits; Japan's NYK Line and Kawasaki Kisen followed. According to UNCTAD, vessel traffic through the strait dropped 97% from pre-blockade averages as of March 7, and 45 Japan-related vessels were stranded in the Persian Gulf.

Oil moved fast. WTI crude, around $67 before the conflict, spiked briefly above $119 in early March. Brent crossed $100 a barrel on March 8 for the first time in four years and peaked at $126.

Mojtaba Khamenei, named Iran's new Supreme Leader on March 9, used his first statement on March 12 to say the blockade would continue and would be used as an instrument of pressure in the war.

The International Energy Agency (IEA) has characterized the crisis as "the largest supply disruption in the history of world oil markets" and authorized a coordinated release of approximately 400 million barrels from strategic reserves across its 32 member nations. However, the market response has been muted, with supply fears remaining firmly intact.

Energy Self-Sufficiency at 13%: Japan's Structural Vulnerability

This crisis has laid bare the fundamental fragility of Japan's energy security.

Japan's primary energy self-sufficiency rate stands at approximately 13%, ranking 37th out of 38 OECD nations. The country depends on fossil fuels for about 80% of its energy supply, and more than 95% of its crude oil comes from the Middle East. Saudi Arabia and the UAE each account for roughly 40% of Japan's oil imports, and virtually all of it transits the Strait of Hormuz.

Since the 2011 Fukushima nuclear disaster, Japan's reliance on fossil fuels has only deepened as nuclear power generation declined. Oil-fired power generation now accounts for only about 7% of electricity output, limiting the immediate impact on the grid. But the problems extend well beyond electricity.

The most pressing concern is naphtha supply. Naphtha, the feedstock for plastics, synthetic rubber, and synthetic fibers, is only 30% domestically produced; the remaining 70% is imported from UAE, Kuwait, Qatar, and other nations, almost entirely via the Hormuz strait. With those supplies cut off, petrochemical companies like Mitsui Chemicals have already begun reducing ethylene production. If the blockade persists, Japan's entire manufacturing sector could face cascading shortages.

Japan does maintain substantial oil reserves, approximately 254 days' worth (about 8 months) between government and private stockpiles. This provides a buffer, but stockpile drawdowns are a stopgap, not a solution. A prolonged blockade would eventually create severe supply constraints.

Record Gasoline at $1.19 a Litre

The double blow of expensive oil and a weak yen is already being felt in everyday life.

According to the Agency for Natural Resources and Energy, the nationwide average retail price for regular gasoline hit 190.8 yen per liter (approximately $1.19) on March 16, an all-time high since records began in 1990. Prices surged 29 yen in a single week, and some stations in Tokyo were charging over 200 yen ($1.25) per liter.

In Amagasaki city near Osaka, regular gasoline jumped from the 140-yen range in early March to the 180s in just weeks. Panicked drivers rushed to fill up before further increases, creating traffic jams that backed up onto the highway.

The government announced the restart of emergency fuel subsidies from March 19, aiming to hold the national average at around 170 yen ($1.06) per liter, with a subsidy of 30.2 yen per liter paid to wholesale distributors. However, the Nissei Research Institute estimates that if Dubai crude reaches $110 per barrel, gasoline could climb to around 204 yen ($1.28) even without the end of subsidies.

The ripple effects extend far beyond the gas pump. RP Topla, a plastics manufacturer in Wakayama Prefecture, reported a 40% increase in raw material costs due to naphtha shortages. Airlines are considering fuel surcharge hikes. Rising logistics costs are expected to push up prices for food and daily necessities across the board.

Economists estimate the energy price surge could add 0.6–0.7 percentage points to Japan's Consumer Price Index (CPI), further squeezing real wage growth that households desperately need.

Will Japan Intervene? The 160-Yen Defense Line

Markets are closely watching whether the Japanese government and BOJ will step in with currency intervention.

Among 15 surveyed foreign exchange specialists, 160 yen per dollar was the most-cited trigger level for intervention. In 2024, Japan actually intervened when the yen hit around 161.

However, intervention expectations are surprisingly low this time around. The key reason: yen weakness driven by oil fundamentals doesn't fit the traditional intervention criteria of "speculative excess" or "disorderly movements." Intervening against real-demand selling is widely seen as limited in effectiveness and short-lived in impact.

The Dai-ichi Life Research Institute forecasts the dollar-yen rate to move within a 150–165 range through 2026, suggesting that even if 160 is breached, authorities would deploy a combination of intervention and BOJ rate hikes as a defense strategy. Nevertheless, the persistence of yen carry trades and the Japan-US interest rate differential continue to exert downward pressure on the yen.

How Do South Korea and Germany Compare?

South Korea and Germany, both major energy importers like Japan, are also reeling from the Hormuz blockade.

South Korea relies on the Strait of Hormuz for about 70% of its crude oil imports. While this is lower than Japan's 95%, the impact is still severe. In terms of daily oil volumes passing through Hormuz, China leads at 5.4 million barrels per day, followed by India at 2.0 million, and Japan and South Korea each at 1.7 million. Initially reluctant to condemn Iran, Seoul ultimately joined a 20-nation statement criticizing the blockade, citing "direct impacts on Korea's energy supply and economy."

Germany had been heavily dependent on Russian natural gas but has diversified its sources since Russia's 2022 invasion of Ukraine. However, the Hormuz blockade has now cut off Qatari LNG shipments to Europe, threatening the EU's target to eliminate Russian LNG imports by 2027.

Comparing energy self-sufficiency rates, Japan stands at approximately 13%, South Korea at about 18%, and Germany at roughly 35%, thanks largely to its aggressive expansion of renewable energy. Germany has pushed renewable electricity generation above 50% of total output, steadily reducing fossil fuel dependence. Japan and South Korea, by contrast, remain heavily influenced by the status of their nuclear power fleets.

What Happened Next: 160 Broke, and Japan Intervened

Events moved quickly after this article was published.

On March 19, US forces launched a military operation to break the blockade. Traffic did not return: MUFG Bank counted just three vessels transiting the strait on March 29. By June, the US and Iran had reached broad agreement on a memorandum covering a ceasefire extension and reopening the strait, and crude fell back to its lowest levels since March. Even so, transit volumes remain around 2% of pre-blockade levels, and some observers now see full recovery slipping to 2027.

On the currency, the 160 line this article flagged as the defence threshold did not hold. On the evening of April 30, the dollar-yen fell abruptly from the high 160s to the 155 range. Finance Minister Satsuki Katayama and Vice Minister for International Affairs Jun Mimura had issued pointed warnings beforehand, and the move is widely read as the first yen-buying intervention since July 2024. The contemporary view that intervention was unlikely against real-demand yen selling turned out to be wrong on the intervention itself.

The effect did not last. The dollar-yen reached 161.95 on June 25 and 162.84 in early July, a roughly 40-year low for the yen. Intervention caps the upside; it does not sever the interest rate gap or the oil bill underneath it.

Gasoline has calmed. Agency for Natural Resources and Energy data put the national average at ¥169.5 on June 8, with the subsidy running at ¥33.3 per litre. That is more than ¥20 below the ¥190.8 peak, but it is a price held down by subsidy rather than by the market.

Structural Change Is Imperative

This crisis has revived concerns about Japan's energy security that date back to the 1973 Oil Shock, the first oil crisis to send shockwaves through the Japanese economy.

After that shock, Japan pursued diversification of oil sources. But rising demand in Asian oil-producing nations and other factors meant that Middle East dependency actually increased over time, reaching the current 95%-plus level, by far the highest among advanced economies.

In the short term, Japan can weather this with strategic reserve releases and fuel subsidies. Over the medium to long term, expanding renewables, safely restarting nuclear plants, and accelerating EV adoption will be essential. But reserves, subsidies and currency intervention are all ways of buying time. The question is what gets built with the time. Until there is an answer, the price at the pump will keep moving every time someone pulls a trigger on the far side of a strait.

Japan is now facing the double blow of a Hormuz blockade and a plunging yen, forcing a fundamental rethink of its energy security strategy. How does your country handle energy policy and currency fluctuations? Are you feeling the impact of the Middle East crisis? We'd love to hear about your country's situation and your personal perspective.

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