# Iran Declares a "Fully Offensive" Turn in Hormuz as the US Deal Lapses and Brent Climbs Past $90

A senior Iranian official told Reuters that Tehran will strike to break the US naval blockade if diplomacy fails, hours before the 60-day memorandum of understanding expired with no extension talks.

- Published: 2026-08-17T05:13:34.495Z
- Canonical: https://polylog.news/2026-08-17/brent-holds-near-87-with-the-strait-of-hormuz-shut-as-iran-p
- Publisher: Polylog (Global desk)
- Section: markets
- Sources: [IRNA (Farsi)](https://www.irna.ir/news/86237410/%D9%82%D8%A7%DA%86%D8%A7%D9%82%DA%86%DB%8C-%DB%B3%DB%B0-%D9%87%D8%B2%D8%A7%D8%B1-%D9%84%DB%8C%D8%AA%D8%B1-%D9%86%D9%81%D8%AA-%DA%AF%D8%A7%D8%B2-%D8%AF%D8%B1-%D9%84%D8%B1%D8%B3%D8%AA%D8%A7%D9%86-%D8%AC%D8%B1%DB%8C%D9%85%D9%87-%D8%B4%D8%AF), [IRNA (Farsi)](https://www.irna.ir/news/86236446/%D9%BE%D9%86%D8%AC-%D9%87%D9%85%D8%AA-%D9%81%D8%B1%D8%B5%D8%AA-%D8%B3%D8%B1%D9%85%D8%A7%DB%8C%D9%87-%DA%AF%D8%B0%D8%A7%D8%B1%DB%8C-%D8%A8%D8%B1%D8%A7%DB%8C-%D8%B4%D9%87%D8%B1%D8%AF%D8%A7%D8%B1%DB%8C-%D8%A8%D8%AC%D9%86%D9%88%D8%B1%D8%AF-%D8%AA%D8%AF%D9%88%DB%8C%D9%86-%D8%B4%D8%AF), [Al Jazeera](https://www.aljazeera.com/economy/2026/8/12/oil-prices-rise-as-attacks-dent-hopes-for-strait-of-hormuz-reopening), [CNBC](https://www.cnbc.com/2026/08/11/oil-prices-today-us-crude-84.html)

Iran has decided to move from a defensive to a "fully offensive" posture in the Strait of Hormuz and the wider region, a senior Iranian official [told Reuters on Monday](https://www.usnews.com/news/world/articles/2026-08-17/iran-threatens-to-go-on-offensive-in-strait-of-hormuz-if-diplomacy-with-us-fails), saying Iranian entities must be ready to escalate and that Tehran would carry out a "timely and precise" military attack to break the United States naval blockade if diplomacy fails. The statement came as the memorandum of understanding (MoU) signed on 17 June by President Donald Trump and Iranian President Masoud Pezeshkian [reached its 60-day expiry](https://www.aljazeera.com/news/2026/8/17/us-iran-memorandum-of-understanding-expires-how-and-why-it-fell-apart). Iran's foreign ministry spokesman, Esmail Baghaei, ruled out any talks on extending it, telling the state news agency Tasnim that no negotiations ever began because Washington had violated the understanding from the outset. Trump said Iran should "put up the white flag of surrender."

Oil moved but did not break its range. Brent rose about 2% to $90.31 a barrel and US crude gained 1.8% to $83.87 [as Iran ruled out an extension](https://www.cnbc.com/2026/08/17/oil-prices-iran-war-strait-hormuz.html), leaving prices inside the elevated band traders have held since the waterway closed. Ship traffic is close to a halt. Three vessels crossed the strait on Sunday, according to data from the analytics firm Kpler.

The two sides continue to dispute who controls the waterway. Tehran says point five of the MoU gives it the right to manage passage, and the secretary of Iran's Supreme National Security Council has added the unfreezing of Iranian funds held abroad as a further condition, alongside the ministry's position that ["as long as the US naval blockade continues, the necessary conditions for the reopening of the Strait of Hormuz do not exist"](https://www.cnbc.com/2026/08/11/oil-prices-today-us-crude-84.html). Washington rejects that reading and says it controls the strait. [Attacks on vessels last week further reduced the prospect of a near-term deal](https://www.aljazeera.com/economy/2026/8/12/oil-prices-rise-as-attacks-dent-hopes-for-strait-of-hormuz-reopening). Brigadier General Yadollah Javani, who heads the political bureau of the Islamic Revolutionary Guard Corps (IRGC), told Iranian state television that his forces are ready to take whatever action the country's defence requires, and [Iranian officials said any American landing operation would need at least 100,000 troops](https://www.aljazeera.com/news/2026/8/17/iran-signals-readiness-for-us-ground-operations-as-mou-expires). The United States Energy Information Administration does not expect Middle East production to return to near pre-conflict levels until early 2027 and forecasts Brent to average $87 a barrel this year.

Inside Iran, the closure compounds an older distortion. The state sets domestic fuel prices far below regional levels, which creates a permanent incentive to move product across borders. The government's enforcement arm in Lorestan province said on Monday that a court had [fined a trader 66.97 billion rials for smuggling 30,000 litres of diesel](https://www.irna.ir/news/86237410/%D9%82%D8%A7%DA%86%D8%A7%D9%82%DA%86%DB%8C-%DB%B3%DB%B0-%D9%87%D8%B2%D8%A7%D8%B1-%D9%84%DB%8C%D8%AA%D8%B1-%D9%86%D9%81%D8%AA-%DA%AF%D8%A7%D8%B2-%D8%AF%D8%B1-%D9%84%D8%B1%D8%B3%D8%AA%D8%A7%D9%86-%D8%AC%D8%B1%DB%8C%D9%85%D9%87-%D8%B4%D8%AF) in Poldokhtar county. Prosecutions of this kind are routine, and they persist because the price gap they arbitrage is set by policy rather than by supply. Capital formation faces the other half of the problem. The head of the economy and investment committee of Bojnourd city council told the same agency that the municipality has [drawn up five thousand billion tomans of investment opportunities](https://www.irna.ir/news/86236446/%D9%BE%D9%86%D8%AC-%D9%87%D9%85%D8%AA-%D9%81%D8%B1%D8%B5%D8%AA-%D8%B3%D8%B1%D9%85%D8%A7%DB%8C%D9%87-%DA%AF%D8%B0%D8%A7%D8%B1%DB%8C-%D8%A8%D8%B1%D8%A7%DB%8C-%D8%B4%D9%87%D8%B1%D8%AF%D8%A7%D8%B1%DB%8C-%D8%A8%D8%AC%D9%86%D9%88%D8%B1%D8%AF-%D8%AA%D8%AF%D9%88%DB%8C%D9%86-%D8%B4%D8%AF), and that each project requires 25 separate approvals from different agencies before it can proceed.

The expiry removes the last formal framework restraining either side, and the dispute now rests on force and endurance rather than on an agreed text. Sanctions and a closed strait cut Iran's external earnings, while controlled prices and administrative barriers push domestic activity toward arbitrage and away from production. That combination determines how long Tehran can sustain the position it has just hardened.

## What this means

A closed Hormuz keeps a supply premium in every barrel priced off the Gulf, which raises input costs for refiners and importers across Asia and Europe and hands income to producers who can ship without transiting the strait. Iran's domestic arrangements determine the duration. Subsidised fuel prices and permit-heavy investment rules mean the economy generates less usable revenue per barrel than its reserves imply, so Tehran's ability to hold out depends more on external cash than on domestic output. The countries most exposed are the large Asian crude importers that lack alternative pipeline routes.

## What to watch

- Whether Iran converts its stated offensive posture into an actual strike on blockade forces or shipping. A first attack aimed at US naval assets rather than at individual merchant vessels would mark a change in kind, not degree, and would price a supply loss that has so far stayed hypothetical.
- Daily transit counts through the strait, which fell to three vessels on Sunday. A sustained return to double-digit crossings would signal a quiet accommodation between the two sides even without a signed agreement, while a run of zero-transit days would confirm a full closure that current oil prices do not yet reflect.
- Whether any third party, particularly Oman, Pakistan or Qatar, reopens a mediation channel now that the MoU has lapsed. New talks would be the clearest indication that the offensive language is a negotiating position rather than a decision already taken.
- The gap between Brent near $90 and the Energy Information Administration's $87 full-year forecast. If prices hold well above that forecast into September, it would mean traders expect the closure to outlast the agency's assumption that Middle East supply recovers by early 2027.