A fresh military exchange in one of the world's most critical energy corridors pushed Brent crude above $101 a barrel on Friday, reigniting fears that the fragile US-Iran ceasefire may not hold.

Oil markets opened sharply higher in Asia on Friday after US military forces and Iranian troops exchanged fire in the Strait of Hormuz, the narrow waterway through which more than a fifth of the world's daily oil and gas supply flows. The incident pushed Brent crude briefly past a 2% gain before it settled up 1.5% at $101.60 a barrel. West Texas Intermediate, the US benchmark, rose 1.1% to $95.87.

The clash is one of the most direct confrontations along the strait since the broader conflict began on 28 February, when the United States and Israel launched coordinated strikes on Iran. It raises immediate questions about whether the ceasefire that President Donald Trump extended indefinitely on 21 April can survive escalating incidents at sea.

What happened in the Strait of Hormuz

The US military said its warships were heading out of the Persian Gulf through the strait when they came under what it described as "unprovoked" attacks involving Iranian missiles, drones and small boats. American forces responded with self-defence strikes. Trump told reporters that three US destroyers were involved in the exchange, that several Iranian small boats had been "completely destroyed," and that missiles targeting the ships were "easily knocked down."

Iran offered a sharply different account. Iranian state media reported that US forces had violated the ceasefire by targeting Iranian vessels, including a civilian oil tanker, and by conducting aerial strikes along the coastline near the strait. Iranian forces said they responded to those strikes by attacking US military vessels and inflicting "significant damage." The US military denied that any of its ships had been hit and said it was not seeking to escalate the conflict.

By later in the session, Iranian state media reported that the situation had returned to normal. Trump, speaking to ABC News, called the exchange "just a love tap."

"The talks are going very well, but they have to understand if it doesn't get signed, they're going to have a lot of pain."

— President Donald Trump, speaking to reporters on Friday

Why oil markets reacted so sharply

The Strait of Hormuz: the world's most important energy chokepoint

The Strait of Hormuz is a narrow passage connecting the Persian Gulf to the Gulf of Oman. At its most constricted point it is only about 33 kilometres wide, yet it serves as the primary export route for crude oil from Saudi Arabia, the UAE, Kuwait, Iraq and Iran. More than 20% of the world's oil and gas shipments transit this single corridor every day, making it the most consequential energy chokepoint on the planet.

That figure alone explains why even a brief and contained exchange of fire provokes an immediate market response. Traders do not need a full blockade to react. The credible possibility of disruption is sufficient to move prices.

The ceasefire is holding, but only just

Analysts have struggled to price the ongoing US-Iran conflict since hostilities began in late February. The April ceasefire brought some relief, but it has clearly not eliminated the risk premium embedded in energy prices. Associate professor Jiajia Yang of Australia's James Cook University noted that Friday's incident reinforced existing concerns that military activity along the strait could further threaten energy shipments through the corridor.

Huifeng Chang, an economics researcher at the National University of Singapore, captured the market mood plainly: traders view the ceasefire as "fragile" and have priced it accordingly, even as both Washington and Tehran attempt to publicly de-escalate after each incident.

Key market drivers at a glance

• A live military exchange occurred in the Strait of Hormuz, the world's single most important oil transit route
• Economists describe the ceasefire as "fragile"; both sides gave conflicting accounts of who fired first
• Iran had previously threatened to block Hormuz in retaliation for US-Israeli strikes beginning 28 February
• Brent crude crossed $101, a psychologically significant level reinforcing the war risk premium
• Unresolved nuclear deal negotiations add a further layer of price uncertainty to forward energy markets

Trump's nuclear deal calculus and Iran's response

Despite the exchange of fire, Trump insisted that negotiations with Tehran are continuing and that the ceasefire technically remains in place. He repeated Washington's core demand: Iran must never develop or acquire a nuclear weapon. He framed the talks as progressing on terms favourable to the United States. "I believe they want the deal more than I do," he said.

That framing carries direct implications for energy markets. A successfully concluded nuclear agreement would theoretically ease existing sanctions on Iranian oil exports, increasing global supply and putting downward pressure on crude prices. A breakdown in talks, or a further escalation of military activity near Hormuz, would have the opposite effect and could tighten supply significantly if Iran moves to restrict commercial shipping through the strait.

Iran's military, for its part, accused the US of acting as the aggressor by targeting an oil tanker and conducting coastal airstrikes. If verified, the involvement of a civilian tanker would represent a meaningful escalation beyond military vessel engagements and could draw additional international scrutiny on both sides.

Future implications: three scenarios for energy markets

Scenario 1: talks succeed, prices moderate

If US-Iran nuclear negotiations produce a framework agreement, sanctions relief on Iranian crude could add one to two million barrels per day of supply to global markets. Combined with a durable ceasefire, Brent would likely retrace toward the $80 to $85 range as the war risk premium dissolves and markets re-price geopolitical stability.

Scenario 2: low-level conflict persists

The most probable near-term outcome is episodic military incidents like Friday's, followed by de-escalatory statements from both sides. In this scenario oil prices remain elevated with a $10 to $15 war premium, shipping insurers continue charging higher rates for Gulf transit, and global growth projections face a mild but persistent headwind from elevated energy costs.

Scenario 3: Hormuz blockade or sustained escalation

The tail risk scenario involves a sustained Iranian move to restrict commercial shipping through the strait or a significant strike on oil infrastructure. In this case, oil prices could spike well above $120 per barrel in the near term. The countries most exposed are Japan, South Korea, India and China, all of which source the majority of their crude imports through the Hormuz corridor.

Conclusion: a market in permanent vigilance mode

Friday's price movement was sharp, fast and only partially reversed. It captures precisely the condition of global energy markets since late February: no longer treating Hormuz as a theoretical risk but as an active one, with traders unwilling to discount the possibility of a major supply disruption simply because both governments issue reassuring statements after each incident.

The core tension is straightforward. Trump wants a nuclear deal, says talks are progressing well, and needs a stable oil market to support the broader US economy. Iran wants sanctions relief and leverage. Meanwhile, the military situation on the water remains volatile, and both sides continue to accuse each other of provocation. Until a durable framework is signed and verified, energy markets will continue to price in the risk. Any future exchange of fire along the Strait of Hormuz will be met with an immediate and significant response from traders around the world.