The Long War: The quarter-by-quarter costs of a continuing Iran war

Key takeaways:

• • • Q2 is a wound that heals if the war stops — Oil spikes, inflation revisions, and supply disruptions are painful but mostly reversible in a short-war scenario. The exception is insurance and risk premiums for Gulf maritime transit, which are permanently repriced.

    • Q3 is a wound that scars — Sustained oil at $130 per barrel changes household and business behavior in ways that don’t snap back. Recession probability crosses the coin-flip threshold and supply chain disruptions cascade into industries far from the Gulf.

    • Q4 is a different body — Even if the war ends, the global economy has rebuilt itself around the disruption. Trade routes, supplier relationships, and risk models have been permanently rewired, especially if there is nothing structural to prevent the Strait from closing again.

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This is the second of a two-part series on the impact of the war with Iran as the conflict continues. In this part, we’ll walk through what a quarter-by-quarter economic scenario would look like if the war continues.

Previously, we made the case that the US-Iran war is unlikely to end quickly. The regime hasn’t collapsed, the asymmetric force controlling the Strait of Hormuz is nowhere near neutralized, and diplomacy seems dead on arrival. Most significantly, the United States military is escalating, not winding down.

While the first part of this series was about the military and diplomatic picture, this piece is about your balance sheet.

What follows is a quarter-by-quarter map of what a prolonged conflict means for the global economy, charted from now through Christmas 2026. We’ll cover how oil, supply chains, GDP forecasts will be revised in real time, and how disruptions that look temporary in Q2 could trigger a permanent rewiring of how the global economy moves goods, prices risk, and sources critical inputs.

Even if your company doesn’t import a single barrel of Gulf crude, you could still get hit by this. Indeed, if you’re plugged into the global economy like the rest of us, you’re going on this ride.

Q2 2026 (April–June): The wound that heals

If the war ends by the close of the second quarter on June 30, most of the damage is reversible — painful, but reversible.

Brent crude is up about 60% since before the start of the war when it was roughly $70 per barrel; and Capital Economics projects that in a short-war scenario, prices could fall back toward $65 by year-end. The interim outlook from the Organisation for Economic Co-operation and Development (OECD) now projects US inflation to be 4.2% for 2026, up sharply from 2.8%, assuming energy disruptions ease by mid-year. If that assumption holds true, it’s likely we’ll be able to muddle through the pain.

Even in the most optimistic scenario, however, Q2 introduces disruptions beyond oil that most people aren’t tracking. The Gulf supplies roughly 45% of global sulfur, and Qatar produces around one-third of the world’s helium, which is essential for semiconductor manufacturing. Further, Qatar’s liquified natural gas (LNG) production was significantly damaged by Iranian strikes.

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Even in the most optimistic scenario, however, Q2 introduces disruptions beyond oil that most people aren’t tracking.

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Further disruptions in fertilizer supply chains could delay spring planting, which could ripple into agricultural yields well into 2027. These effects don’t snap back the moment oil flow normalizes; they have their own timelines.

And here’s the one thing that doesn’t reverse even in the best case — risk premiums. The Strait of Hormuz was priced as a chokepoint that would never actually close. So when it did, that repricing is permanent and will be felt across the world as risk around other too important to fail chokepoints is itself reevaluated and priced higher.

Q3 2026 (July–September): The wound that scars

If a Q2 end to the war represents a recoverable spike, a Q3 end is where the word structural starts showing up in the discussion.

Capital Economics models Brent at roughly $130 per barrel — or roughly 14% higher than where it is now — in a prolonged scenario. At those prices, the damage stops being abstract. And Moody’s Analytics chief economist Mark Zandi estimates that every sustained $10-per-barrel increase costs the average US household roughly $450 per year. At $130 (nearly double pre-war levels) that’s approaching $2,700 per family. That is the kind of money that changes behavior.

In this case, recession becomes “difficult to avoid,” Zandi says, especially if the cost of oil stays elevated for months — and by Q3, it would have. Moody’s recession probability model was pushing 50% in late-March when oil was $108 per barrel. At $130, the math speaks for itself.

Again, in this scenario, the damage fans out beyond energy. Fertilizer shortages hit crop yields, and helium disruptions cascade into semiconductors, automotive, and medical devices. The potential impact on AI-related manufacturing alone could spook investors already primed to see AI as a bubble. Capital Economics projects Eurozone growth at 0.5% and Chinese growth below 3%. Emerging markets could face forced rate hikes that deepen their own recessions.

This is the quarter in which contingency plans become operating assumptions. The question is no longer When does this go back to normal? — rather the question is whether normal is coming back at all.

Q4 2026 and beyond: The different body

Here’s what most forecasts don’t capture about a war that continues passed Q4: It almost doesn’t matter whether the war is still active or not. The damage has changed shape, and it’s no longer about what the conflict is doing to the global economy. Instead, it’s about what the global economy has done to itself in response.

Companies that spent Q2 and Q3 diversifying away from Gulf suppliers have now spent real money building alternatives. They are not going back to their pervious pathways even if there is a ceasefire. The sunk costs make the reversal unthinkable, and the memory of this conflict makes it irrational. No supply chain director is walking into a boardroom to recommend re-concentrating risk in a chokepoint that closed once and might close again.

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The prudent approach for companies remains clear. They should plan for the war to last into at least Q2, probably Q3, with structural effects persisting beyond.

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Because, of course, it could close again. If Iran emerges weakened but intact, which is the most likely outcome per multiple intelligence assessments, the result is a hostile state with every incentive to reconstitute its asymmetric capabilities the moment the pressure lifts.

Companies are thus going to reroute their future supplies around the Strait rather than through it. High oil prices and the potential for global shortage will also further accelerate green energy initiatives or alternate fuel sources across the globe as oil security reenters geopolitical calculations. Most importantly, every organization’s supply chain will need a reevaluation in light of an increasingly dangerous world, with expensive secondary supply chains becoming more a necessity than a luxury.

That’s the real legacy of a war continuing past the end of this year. Not oil prices on any given day or even insurance premiums, but the permanent repricing of an assumption. The war didn’t just disrupt the flow of goods through the Strait of Hormuz, it broke the premise that some geographies were too big to fail and would be protected and kept open. Once that premise is now broken so thoroughly companies will need to reevaluate whether the concentration of risk in individual areas is a luxury they can afford. Many will find the answer to be no, resulting in an increased push to diversify risk away from single points of failure.

The planning imperative

Fortunately, the best-case scenario remains possible. However, it requires Iran accepting terms it has publicly rejected as existential, its navy being neutralized despite retaining significant asymmetric combat capability, a coalition materializing from countries that have refused to send warships, and mine-clearance operations succeeding with the deck stacked against them. Only then, we’ll see if civilian traffic is willing to risk billions of dollars that the clean-up job was done right. Each is possible, but the odds remain slim.

The prudent approach for companies remains clear. They should plan for the war to last into at least Q2, probably Q3, with structural effects persisting beyond. They should model energy prices at between $120 and $150 per barrel, not $70. The smart companies are the ones building optionality now because the cost of flexibility is far lower than the cost of being caught flat-footed in September.

Four weeks ago, the assumption was that the Strait of Hormuz was too important to close. However, it did, and the assumption that it will reopen quickly deserves the same scrutiny.

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You can find out more about the geopolitical and economic situation in 2026 here