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Iran-USA: Strikes Resume, Talks Restart, and the Pressure Spreads Beyond Hormuz
Our monthly risk briefing on the Iran–USA war, September 2026.
Today we publish the September edition of our Iran-USA monthly geopolitical briefing. We assess the overall risk arising from the war as High and rising. The full briefing, with our risk ratings, scenarios and 139 footnoted sources, is available to download below.
The month in brief
September brought the return of sustained US military action against Iran, after a summer in which Washington had relied mainly on economic pressure. On the 1st September, US Central Command struck Islamic Revolutionary Guard Corps air-defence, radar, maritime, mine-laying and communications sites along Iran's southern coast. Iran retaliated with missile and drone attacks on US bases in Jordan, Bahrain, Kuwait and Iraq.
The fighting then moved to the water. After Iran fired ballistic missiles at a US aircraft carrier and destroyer, US forces struck 3 Iranian oil tankers on the 5th September and destroyed 5 more on the 8th September. The Strait of Hormuz remains the war's centre of gravity, contested by 2 rival control regimes: Iran demands that ships seek its permission to transit, while the United States blockades vessels trading with Iranian ports. Commercial traffic through the strait stayed around 90% below pre-war levels throughout the month.
The pressure spreads
The most significant development was the spread of disruption to the routes that bypass Hormuz. Saudi Arabia shut its East-West pipeline, its main alternative export route, after it was hit by drones launched from Iraq. Yemen's Houthis took control of the country's Red Sea coast and of Mayun (Perim) island in the Bab al-Mandab, putting a second chokepoint under pressure. As a result, we have rated both Energy & Commodities and Shipping & Trade Routes as Severe. These are the first Severe ratings in our Tier 1 series.
Talks resume, but the gap remains
Diplomacy restarted late in the month. On the 22nd September, US envoys Steve Witkoff and Jared Kushner held mediated talks with an Iranian delegation led by Foreign Minister Abbas Araghchi on the sidelines of the UN General Assembly. These were the first such contacts since the interim ceasefire collapsed in July. Tehran followed with a 7-day plan: Iran would reopen the strait once Washington lifted its naval blockade, waived oil sanctions and released frozen Iranian assets. On the 26th September, President Trump rejected the plan as unacceptable. The Wall Street Journal has reported that he expects a renewed bombing campaign after the US midterm elections on the 3rd November.
Washington's main instrument remains economic. Under Operation Economic Outcast, the US Treasury designated Russia's VTB Bank for helping Iran evade sanctions and extended pressure to companies in third countries. The UAE, Oman and others then suspended flights by Iranian airlines.
Our judgement
We judge it highly likely that the war continues without a settlement through the US midterms, and we assess a large-scale US bombing campaign after the elections as a realistic possibility. The return to talks does not yet change that outlook. Washington and Tehran remain divided on sequencing, and domestic politics on both sides narrow the room for compromise.
Why it matters for European readers
For European readers, the sharpest exposure is energy. Oil prices broke above $100 a barrel in early September, and European gas prices rose above €73 per megawatt hour, the highest level since late 2022. This comes just as the heating season begins. European airlines remain restricted across the Gulf under EASA's conflict zone advisories. In the Red Sea, the EU's Operation Aspides has raised its alert level, and Brussels has asked member states for more warships to escort commercial shipping.
What we are watching
Over the coming month, we are watching for 5 things:
whether mediated talks resume after Trump's rejection of Tehran's plan;
any signal of a US decision on strikes after 3 November;
whether Iran formally declares its restricted zone in the strait;
whether the Houthis extend attacks beyond Saudi-linked shipping;
whether EU foreign ministers agree to reinforce Operation Aspides on the 12th October.
Read the full briefing
The full September briefing sets out our Key Judgements, risk ratings across 10 categories, a detailed review of the month, our assessment and scenarios for the next 1-3 months, and implications for energy, sanctions compliance, shipping, cyber and aviation.
Westbrook Advisory publishes monthly risk assessments for 4 Tier 1 conflicts and quarterly assessments for Tier 2 and Tier 3 files. Subscribe to receive each edition as it is published. For tailored analysis for organisations with exposure to this conflict, contact Advisory@westbrookadvisory.co.uk.
Westbrook Advisory produces this assessment independently. It is for general information only and does not constitute financial, legal, investment or security advice.
