The analytical shift

A months-long closure changes the question.

A CIA assessment delivered to administration policymakers in May 2026 concluded that Iran can sustain pressure on the Strait of Hormuz for at least three to four months before facing severe economic hardship. The intelligence community's judgment, more considered than the administration's public position, also found that Tehran retains approximately 70–75% of its pre-conflict missile stockpiles and has been able to reopen most of its underground storage facilities. Iran is drawing down oil field output to preserve infrastructure and exploring overland export routes through Central Asia.

The practical implication of a months-long timeline is that this is no longer a spike scenario. It is a sustained disruption, and the analytical question shifts from "what happens if Hormuz closes?" to "which importers absorb what costs, and for how long?"

The Narrows bilateral dependency model answers that question at the country-pair level, covering real trade flows rather than corridor allocations. The figures below are the result.

The importer exposure map

Two categories of risk: cost exposure and supply gap.

Hormuz carries a disproportionate share of global crude petroleum and LPG flows. Among the nations with meaningful dependency, two broad categories of risk emerge: importers who can reroute via Cape of Good Hope (at cost) and those who face a supply gap with no viable maritime alternative.

Bilateral Hormuz dependency matrix: crude petroleum, 2023
Importer Dep. % Annual exposed 30d VaR Rerouting verdict
Highest percentage dependency
Japan83.0%$67.1B$5.6BCape viable · +12d · no supply substitute at scale
South Korea73.0%$62.9B$5.2BCape viable · +12d · limited strategic reserve depth
Greece54.6%$8.5B$0.7BGrade-configured refiners · low substitution flexibility
India72.7%$69.6B$5.7BCape viable · grade flexibility limited · volume large
Significant volume exposure
China46.3%$167.4B$14.0BAtlantic/ESPO partial substitution · Cape +13d · months to execute at scale
United States9.3%$18.1B$1.5BAtlantic Basin alternatives · SPR buffer
Moderate percentage, structural exposure
Indonesia28.6%$3.1B$0.3BDual exposure: +47.8% LPG dependency compounds 28.6% crude risk
Brazil48.1%$3.3B$0.3BNon-reroutable: grade substitution path, not vessel diversion
France13.4%$4.6B$0.4BAtlantic alternatives close · SPR buffer · cost exposure not supply gap
Germany6.6%$4.0B$0.3BLow base dependency · SPR buffer · well covered
Canada14.5%$2.8B$0.2BNon-reroutable: domestic production ramp-up path

Source: Narrows Chokepoint Model v0.3, WITS UN Comtrade 2023 bilateral data. Dep% = Gulf-origin exposed value ÷ total commodity imports. Oman excluded from Gulf-exposed set (terminals on Gulf of Oman side, outside Strait). 30d VaR = exposed value × 30/365. Tier 1 bilateral data for all rows.

The China number in context
China's $167.4B annual Hormuz exposure is the largest volume in the matrix, but 46.3% leaves meaningful headroom for substitution: Russian ESPO at approximately 18% of Chinese crude imports, West African and Brazilian grades can partially substitute Gulf crude. The constraint is execution speed: a meaningful substitution exercise at this volume takes months, not weeks. A three-to-four month disruption is precisely the timeframe in which China's substitution flexibility is tested most severely.

Greece carries the highest percentage exposure among the European importers at 54.6%, but the structural risk is different from Japan or Korea. Greek independent refiners are configured around specific Gulf crude grades and have limited flexibility to substitute quickly. The dollar volume is smaller ($8.5B), but for P&I underwriters with Greek refinery or tanker clients, this is an acute concentration risk rather than a manageable cost event.

Brazil and Canada show meaningful crude dependency (48.1% and 14.5% respectively) but are flagged as non-reroutable, meaning the mitigation path runs through domestic production ramp-up and grade substitution, not vessel diversion. The exposure is real; the cost structure is different.

Rerouting economics

For those who can reroute, the Cape of Good Hope is the only option. Here is what it costs.

For importers who can reroute, there is no short bypass. The Cape of Good Hope adds 11–14 days depending on vessel class and origin port. The economics of that decision, modelled across the vessel classes transiting Hormuz:

Cape of Good Hope rerouting cost: 90-day disruption window
Vessel class Detour (days) Voyage cost overrun Est. voyages / 90d Class total
VLCC12$1.20M160$224M
Aframax14$0.70M120$99M
Capesize13$0.65M60$43M
Handymax11$0.33M80$29M
Container13$0.71M100$86M
Total $480M

The $480M figure is a direct fleet operating cost (bunker plus charter rate, excluding cargo carrying charges) across vessel classes over 90 days at full closure. The annualised trade value those vessels are carrying is orders of magnitude larger.

The 12-day VLCC detour is also a liability extension event. Every day a laden VLCC spends at sea is an additional day of P&I exposure. For underwriters writing accumulation on the Cape route during a Hormuz disruption, the concentration of diverted tanker traffic around the Cape creates its own modelling challenge: the same vessels that are no longer in the Gulf are now transiting a single alternative corridor in elevated numbers.

The LPG dimension

The exposure that is absent from almost every current analysis.

The crude petroleum story dominates coverage. On the bilateral data, the LPG exposure in Southeast Asia is sharper than almost anything in the crude picture, and has received almost no analytical attention.

Bilateral Hormuz LPG dependency: Southeast Asia, 2023
Importer LPG Dep. % Annual exposed Supply substitute?
India97.6%$11.3BNo viable alternative at scale
Philippines83.2%$0.5BNo alternative · cooking fuel dependency
Vietnam77.6%$0.9BNo alternative at scale
Thailand76.0%$0.8BNo alternative · petrochemical feedstock
Malaysia68.6%$0.2BNo large-scale alternative
Indonesia47.8%$1.7BCompound: +28.6% crude exposure
China50.5%$10.0BUS propane partial, contractually committed

To calibrate these figures: Japan's crude dependency on Hormuz, which has driven Japanese government reserve policy for decades and prompted the largest strategic reserve release in history in March 2026, is 83.0%. The LPG figures for Southeast Asia sit in the same range. The difference is that no equivalent strategic reserve infrastructure exists for LPG, and the commodity market is structurally distinct.

Why LPG is not the same risk as crude
Gulf LPG, primarily from Qatar and the UAE, moves to Southeast Asian importers aboard purpose-built pressurised LPG carriers. If Hormuz closes, that cargo is physically trapped at the loading terminal. An empty carrier can in principle seek alternative supply, but no alternative source at comparable scale exists: US propane is largely committed to existing contracts, and an Alaskan or US Gulf Coast voyage to Southeast Asia is economically extreme. Australian LPG associated with LNG production is available but not at Qatari scale. In Thailand and the Philippines, a supply shortfall is a domestic energy access event.
The bottom line

Three to four months is long enough to exhaust reserves, restructure spot markets, and begin affecting refinery configurations.

The importer exposure is not uniformly distributed. Japan and South Korea sit at 83.0% and 73.0% crude dependency with limited short-term substitution options. China at 46.3% has the largest absolute volume exposed but some substitution flexibility, at the cost of months of execution time and a Cape rerouting premium. Greece has high percentage exposure with low refinery flexibility. Southeast Asian LPG importers carry dependency figures in the 75–85% range for a commodity with no viable alternative supply source.

A three-to-four month disruption is also long enough for the rerouting cost to move from an insurance event to a macroeconomic one. The $480M 90-day fleet overrun is a direct operating cost. The carrying cost on $31.8B of trade value held at sea for additional weeks is a separate and larger number.

What the geopolitical coverage cannot tell you is which specific importers are on the hook, by how much, and through which commodity. That is what the bilateral trade data shows, and what sustained disruption planning requires.

Data and methodology
Bilateral dependency figures derived from the Narrows Chokepoint Dependency Simulation Model v0.3 (May 2026). Data source: WITS UN Comtrade 2023 bilateral import data. Dep% = Gulf-origin exposed value ÷ total commodity imports of that commodity. Oman excluded from Hormuz-captive supplier set: loading terminals (Mina al-Fahal, OQ Fertilizers Sur) are on the Gulf of Oman side of the Strait and do not transit Hormuz. All crude petroleum and LPG figures are Tier 1 bilateral data: real country-pair flows validated against WITS and cross-corroborated against IEA, METI, and S&P Global where available. Japan 83.0% (CDM v2 2023 bilateral; vs METI-reported 95.9% FY2024 Middle East dependency (S&P Global, August 2025); difference attributable to Oman exclusion, year, and updated bilateral flow data). Rerouting cost estimates: VLCC bunker $55k/day, charter $45k/day; Aframax $28k/$22k; Capesize $32k/$18k; Handymax $18k/$12k; Container $28k/$17k. CIA assessment sourced from reporting by The Washington Post, 7 May 2026. All model assumptions are substitutable. Contact fysh@narrows.io to run a scenario against your specific inputs.