The US-Iran peace deal just wavered. Here is what this means for these ASX shares

The US-Iran peace deal is showing fresh signs of strain after Iran re-closed the Strait of Hormuz.

Peace, it turns out, is easier said than done.

The market has turned jittery after Iran said it had re-closed the Strait of Hormuz over the weekend following Israeli strikes on Lebanon.

That news lands just days after the US and Iran signed an interim peace deal and oil began flowing through the Strait again, sending prices sharply lower.

US and Iranian officials are now in Switzerland for further discussions, but the renewed closure shows just how fragile the agreement remains.

For these ASX shares, that uncertainty has direct and immediate implications.

Young woman thinking with laptop open.

Image source: Getty Images

How oil prices have whipsawed on peace deal headlines

The speed of the reversal has been extraordinary.

Oil prices fell to US$76.64 a barrel for WTI and US$79.38 a barrel for Brent on Friday, as traders sold down prices following the peace deal signing and the resumption of shipping through Hormuz.

That fall came after months of extreme volatility.

Brent crude has previously bounced following fresh US attacks on Iranian targets, only to fall again days later on renewed peace optimism.

The market has now whipsawed in both directions multiple times since the conflict began on 28 February 2026. Today's renewed Strait closure adds yet another reversal to that pattern.

What it means for Woodside, Santos, and Beach Energy shares

Woodside Energy Group Ltd (ASX: WDS) has been one of the biggest beneficiaries of elevated oil prices in 2026, rising 21% year to date.

A renewed closure of the Strait would likely reverse that recent decline and push the share price higher again.

However, Woodside's longer-term investment case is not solely dependent on the oil price, with Scarborough LNG now 94% complete. The project is on track for first cargo in Q4 2026, providing earnings support regardless of where oil settles.

Santos Ltd (ASX: STO) is up approximately 18% year to date and fell 8% in a single session when the original peace deal news broke. This illustrates just how sensitive the stock remains to Middle East headlines.

Santos' Barossa LNG project is already producing at 75% of its planned 2026 rates, giving the business some insulation from oil price swings.

Beach Energy Ltd (ASX: BPT) remains the most leveraged of the three to oil price movements, given its smaller size. The company has continued to underperform even during periods of rising oil prices due to its own production guidance downgrade earlier in FY 2026.

Why the broker community remains divided on these ASX shares

Peak Asset Management holds a hold rating on Woodside. The asset manager has noted that the company continues to execute strongly operationally even as quarterly production fell 8% due to seasonal weather events, with the average realised oil price rising 11% in Q1 2026.

This nuanced view, constructive on operations but cautious on the unresolved geopolitical backdrop, reflects the difficulty brokers face in pricing these stocks while the Hormuz situation remains this unsettled.

The key lesson for investors

The most important thing for ASX investors to understand is that this situation remains unresolved.

The Strait of Hormuz has opened and closed multiple times since February. Each reversal has triggered a sharp and immediate share price reaction across Woodside, Santos, and Beach Energy.

Positioning a portfolio for a single, confident outcome carries real risk given how quickly this situation has shifted in both directions over the past four months.

Foolish Takeaway for these ASX shares

The US-Iran peace deal has wavered just days after being signed, with Iran re-closing the Strait of Hormuz over the weekend.

For Woodside, Santos, and Beach Energy shareholders, that means the volatility that has defined 2026 is unlikely to disappear soon.

Investors in all these ASX shares should expect continued share price swings as the situation in the Middle East continues to evolve in real time.

Motley Fool contributor Mark Verhoeven has no position in any of the stocks mentioned. The Motley Fool Australia's parent company Motley Fool Holdings Inc. has no position in any of the stocks mentioned. The Motley Fool Australia has no position in any of the stocks mentioned. The Motley Fool has a disclosure policy. This article contains general investment advice only (under AFSL 400691). Authorised by Scott Phillips.

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