Ship traffic through the Strait of Hormuz has picked up since Iran and the United States signed an interim agreement to end a war that disrupted global oil supplies and fuelled inflation. However, uncertainty over who will control the vital waterway and whether vessels may eventually be charged tolls continues to complicate negotiations aimed at securing a lasting peace.
Tehran and Washington clashed once again over the Strait of Hormuz over the weekend. Citing Israel's latest strikes on Lebanon, Iran declared that it had reclosed the strait, a claim the United States swiftly disputed. Maritime tracking data showed that dozens of vessels transited the waterway on Saturday and Sunday, although the number remained well below pre-war daily averages.
President Donald Trump has suggested that the United States could impose its own tolls on ships using the strait if a final agreement with Iran is not reached during the 60-day negotiating period. Passage through the strait had been free before the war, but Iran last month established a new government authority to collect fees from ships and has maintained that vessels must continue registering with the Persian Gulf Strait Authority.
No single country owns the Strait of Hormuz, which borders both Iran and Oman. Under last week's memorandum of understanding, Iran will continue to manage the strait while holding talks with Oman and six other Gulf states to determine the future administration and maritime services of the waterway. As part of the interim deal, Iran agreed not to levy tolls on transiting vessels for 60 days.
Legal experts and maritime organisations have repeatedly warned that introducing tolls would overturn decades of international maritime practice. Even if Washington and Tehran reach a permanent agreement, analysts believe it could take months for shipments of oil, natural gas, fertiliser and other commodities to return to pre-war levels.
Data and analytics firm Kpler said its tracking showed that 71 ships passed through the Strait of Hormuz between Friday and Sunday, with a peak of 35 crossings on Saturday. Before the conflict erupted in late February, when the United States and Israel launched strikes on Iran and Tehran retaliated by effectively closing the waterway, between 100 and 130 vessels typically transited the strait each day.
As part of the interim framework, Iran agreed to complete demining operations within 30 days and remove "technical and military obstacles" affecting shipping. Iran's chief negotiator and Parliament Speaker, Mohammad Bagher Qalibaf, told state media on Monday that Tehran would manage the strait in accordance with international maritime law.
The main central shipping lane remains mined and closed. Ships are instead using a northern route through Iranian waters or a southern route through Omani waters. Kpler said caution remains evident, with many vessels adhering to Iran's designated route or concealing their movements by switching off their transponders.
During the early stages of the conflict, Iran threatened to target ships attempting to pass through the Strait of Hormuz without its approval and introduced what shipping analysts described as a "pay-to-pass" system. In early April, Tehran also demanded the right to collect tolls as a condition for relinquishing its effective blockade of the waterway.
Although the Trump administration imposed sanctions on the Persian Gulf Strait Authority last month, accusing Tehran of attempting to extort global maritime trade, Trump later suggested that the United States could also impose charges on ships for what he described as "services rendered as the Guardian Angel to the countries of the Middle East".
The administration has yet to explain how such charges would be implemented if negotiations fail. Shipping analysts have expressed surprise at the extent of authority the interim agreement leaves in Iran's hands.
"Almost all the power goes to Iran to determine the arrangements going forward. That's what we really need clarity on," said Philip Belcher, Marine Director at Intertanko, the international association representing independent tanker owners.
During the early stages of the conflict, Iran threatened to target ships attempting to pass through the Strait of Hormuz without its approval and introduced what shipping analysts described as a "pay-to-pass" system. In early April, Tehran also demanded the right to collect tolls as a condition for relinquishing its effective blockade of the waterway.
Although the Trump administration imposed sanctions on the Persian Gulf Strait Authority last month, accusing Tehran of attempting to extort global maritime trade, Trump later suggested that the United States could also impose charges on ships for what he described as "services rendered as the Guardian Angel to the countries of the Middle East".
The administration has yet to explain how such charges would be implemented if negotiations fail. Shipping analysts have expressed surprise at the extent of authority the interim agreement leaves in Iran's hands.
"Almost all the power goes to Iran to determine the arrangements going forward. That's what we really need clarity on," said Philip Belcher, Marine Director at Intertanko, the international association representing independent tanker owners.
Legal experts argue that imposing tolls in the Strait of Hormuz would violate one of the fundamental principles of international maritime law: the right of peaceful transit.
That principle is enshrined in the United Nations Convention on the Law of the Sea (UNCLOS), which entered into force in 1994. The treaty guarantees ships the right of unimpeded transit passage through more than 100 international straits, including the Strait of Hormuz. Unlike natural waterways, however, artificial canals such as the Panama Canal and the Suez Canal may lawfully charge transit fees.
Oman is among more than 170 countries that have ratified UNCLOS, although neither the United States nor Iran is a party to the convention. Maritime organisations nevertheless argue that its core principles are widely recognised under customary international law.
James Kraska, Professor of International Maritime Law at the U.S. Naval War College and a visiting professor at Harvard Law School, noted that both the United States and Iran are members of the International Maritime Organization (IMO) and parties to the International Convention for the Safety of Life at Sea (SOLAS).
According to Kraska, fees in international straits may only be charged at recognised ports or for services specifically requested by ships, such as navigational assistance through hazardous waters.
"If Iran wants to apply those to everybody, then it has to adjust the traffic separation scheme rules, and that can only be done through the member states of the International Maritime Organization," he said.
"You can't impose fees for a ship exercising its right of transit passage. So the bottom line is that fees in this context are simply not lawful."
Kraska noted that countries have occasionally shared the costs of maintaining strategic waterways. Indonesia, Malaysia and Singapore, for example, worked with the IMO and other countries to establish a cooperative funding arrangement for the Strait of Malacca. However, that system relied on negotiated state contributions rather than charges imposed on individual ships.
Conditions in the Strait of Hormuz have shifted rapidly throughout the conflict. Although prospects for shipping have improved since Iran and the United States agreed to extend their ceasefire, uncertainty remains.
"There is still a degree of nervousness around the situation," said Marcus Baker, Global Head of Marine, Cargo and Logistics at insurance brokerage Marsh.
Baker said insurers remain supportive of shipowners seeking to resume operations, but noted that the interim agreement contains no provisions guaranteeing toll-free passage beyond the current 60-day negotiating period.
"We'll see what the next six weeks brings," he said.