Iran’s Revolutionary Guards said ships should avoid the main navigation zone and instead follow designated entry and exit paths to reduce the risk of collision with naval mines.

“All ships intending to transit the Strait of Hormuz are hereby notified they should take alternative routes for traffic,” the statement said, emphasizing maritime safety concerns.

The announcement follows Tehran’s agreement to temporarily reopen the strategic strait as part of a two-week truce reached with Washington. The ceasefire was agreed late Tuesday, shortly before a deadline set by U.S. President Donald Trump for Iran to comply with demands related to the reopening of the passage.

The Strait of Hormuz is a critical global energy corridor, through which roughly one-fifth of the world’s oil supply typically passes.

Iran had effectively restricted traffic through the route since early March, contributing to a surge in global energy prices and heightening concerns over supply disruptions.

The designation of alternative routes signals continued operational risks in the waterway despite the ceasefire, underlining the fragile security environment and the potential for further disruption to global shipping and energy markets.

Willie Walsh, director general of the International Air Transport Association, told reporters in Singapore that while crude prices had fallen below $100 per barrel following a U.S.-Iran ceasefire announcement, jet fuel costs were likely to remain elevated due to constraints on refining output.

“If it were to reopen and remain open, I think it will still take a period of months to get back to where supply needs to be given the disruption to the refining capacity in the Middle East,” Walsh said, adding that the region is critical to global supply of refined products beyond aviation fuel.

The Strait of Hormuz, which carries about a fifth of the world’s oil trade, has been heavily disrupted during the recent conflict, squeezing fuel availability and driving up costs across the aviation sector.

Airlines in Asia have responded by cutting flights, carrying additional fuel from origin airports and adding refueling stops, measures that have increased operational costs for carriers already dealing with a sharp rise in jet fuel prices.

The impact has been most acute in import-dependent markets such as Vietnam, Myanmar and Pakistan, where supply constraints have tightened further after China and Thailand halted jet fuel exports and South Korea capped shipments at previous levels.

Walsh said a resumption of crude flows could encourage exporters such as China and South Korea to restart shipments of refined products, easing pressure on the market over time.

However, he noted that higher refinery margins, known as crack spreads, would be needed to incentivize increased jet fuel production.

“There is capacity available once we get the crude oil flowing, but it’ll take a little bit of time,” Walsh said.

A fuel reservoir at Primorsk caught fire after a drone strike, Alexander Drozdenko, governor of the Leningrad region, said on Telegram. Separately, Ust-Luga operations were halted due to a drone alert in the surrounding area, the sources said.

Both ports, located in Russia’s northwestern Leningrad region, handle the bulk of the country’s seaborne crude oil and refined fuel exports from its western outlets, making them critical nodes in Russia’s energy supply chain.

The suspensions underscore growing vulnerabilities in Russia’s energy infrastructure as drone attacks increasingly target logistics and export facilities. While the extent of damage and the expected duration of the halt were not immediately clear, any prolonged disruption could tighten export availability from Baltic routes.

Transneft, Russia’s state-controlled oil pipeline monopoly that operates both Primorsk and Ust-Luga, did not immediately respond to a request for comment.

Primorsk and Ust-Luga serve as key gateways for Russian crude and petroleum products destined for international markets, particularly in Europe and beyond via maritime routes. Interruptions at these ports can affect shipping schedules, storage logistics and broader supply balances.

The incidents come amid heightened geopolitical tensions and a pattern of attacks on energy infrastructure, raising concerns over the resilience of supply networks and potential knock-on effects in global oil markets.