Iran said foreign ships are allowed to cross the Strait of Hormuz, as long as they aren’t supporting acts of aggression against the country, and follow regulations put in place by Tehran. 

The nation made the comments in a letter circulated to members of the International Maritime Organization on March 24, adding that countries could benefit from safe passage “in co-ordination with the competent Iranian authorities.” The original letter from Iran was dated March 22, the IMO said. 

Iran has started charging transit fees on some commercial vessels passing the Strait of Hormuz, people familiar with the matter have said, the latest sign of its control over the world’s most important maritime energy route. The war in the Middle East has all but stopped traffic through the waterway — a small handful of ships appear to have transited through by taking a route that hugs the Iranian coastline. 

While Iran’s Supreme Leader Mojtaba Khamenei has already said Iran should keep the strait shut, the letter sets out a clearer and more nuanced position. It’s yet another example of the country claiming sovereignty over the waterway, with the war now in a fourth week.

The near-halt to ship transits via Hormuz — through which about a fifth of the world’s oil and gas, along with vast amounts of food, metals and other materials are shipped every day — has sent the prices of vital commodities soaring. In Asia, a region heavily reliant on energy imports, billions of people are dealing with gas outages and preparing for fuel rationing.

Commodities markets have been exceptionally volatile as traders try to gauge when the war will end and Hormuz will be reopened. Though oil advanced on March 24, on renewed fears of an escalating conflict, futures may plunge on any sign that vessels will be able to move more freely through the waterway.

In the letter on March 24, Iran said “non-hostile vessels, including those belonging to or associated with other states, may — provided that they neither participate in nor support acts of aggression against Iran and fully comply with the declared safety and security regulations — benefit from safe passage through the Strait of Hormuz in co-ordination with the competent Iranian authorities.”

The Islamic Republic said it “restricted the passage of vessels belonging to or associated with the aggressors and those participating in their acts of aggression.”

It added that the full restoration of security and stability in the Strait is contingent on the end of military threats in the region.