Uncertainty surrounds how the strategic Strait of Hormuz will operate following a two-week ceasefire between the United States, Israel and Iran.
A major escalation of the Middle East war was narrowly averted on Tuesday evening after Iran and the United States agreed to a truce and to enter negotiations to permanently end the devastating six-week conflict.
The pause in US strikes is contingent on Iran reopening the vital waterway, through which roughly a fifth of global oil supplies pass.
The war brought maritime traffic in the strait close to a standstill, sending global oil and gas prices sharply higher. US President Donald Trump had threatened to "wipe out an entire civilisation" if Iran failed to reopen the route.
However, a full resumption of shipping has yet to be guaranteed. Have any ships passed? Shippers said on Wednesday they needed more clarity on the terms of the US-Iran ceasefire before resuming transit through the Strait of Hormuz, as Iran issued fresh warnings about any vessels attempting to sail through the waterway.
Iran said it would offer safe passage in coordination with its armed forces, though its coastguards warned on Wednesday that any ship attempting to sail without permission would be "targeted and destroyed".
The first vessel had transited the Strait with Iran's permission following the ceasefire, its state TV said on Wednesday.
The ship's identity was not immediately clear, but MarineTraffic data showed two Greek-owned and one Chinese-owned bulk carriers passing through since early Wednesday.
Iran has previously agreed safe-passage arrangements with several countries, including India and Iraq.
Major shipping companies remained cautious.
Shipping journal Lloyd's List estimates that around 800 ships have been stuck in the Gulf since the end of February, when the war started.
Denmark's Maersk said the ceasefire may create transit opportunities for vessels, but did not yet provide full maritime certainty.
German container carrier Hapag-Lloyd said it needed to see that the ceasefire holds before starting to take orders for selected markets. Iran and Oman at odds over transit fees? A dispute has reportedly emerged between Iran and Oman over proposed transit fees for ships passing through Hormuz.
Iran has pushed for the right to charge vessels for safe passage, arguing that it was responsible for securing the waterway during the ongoing conflict. Some Iranian officials have framed the strait as a "corridor" where fees are justified in exchange for protection and regulation.
But Oman – whose territorial waters include part of the internationally recognised shipping lanes – has not publicly endorsed such measures and has instead focused on ensuring the smooth and uninterrupted flow of maritime traffic.
Oman was hit several times by Iran during the conflict, but less than its Gulf neighbours, particularly the United Arab Emirates, which bore the brunt of Iranian drones and missiles.
Under international maritime law, particularly the UN Convention on the Law of the Sea, ships have the right to "transit passage" through international straits without interference or fees, except for specific services.
This means Iran’s proposal could be seen as highly controversial and widely opposed by other countries, which argue it could set a dangerous precedent and effectively allow control over a key global trade route.
Any disruption or new costs imposed on shipping could have major implications for global trade and energy prices. A lot of work to do US Defense Secretary Pete Hegseth said on Wednesday that the Strait of Hormuz is open, and the US military would be "hanging around" in the Middle East to ensure Iran complies with the ceasefire.
Islamabad will soon host talks between the Iranian and US delegations to cement the fragile truce.
British Prime Minister Keir Starmer said on Wednesday there was still a lot of work to do to reopen the Strait of Hormuz, speaking during a visit to Saudi Arabia.
"We now ... have a ceasefire, but there’s a lot of work to do, as you will appreciate, a lot of work to make sure that that ceasefire becomes permanent and brings about the peace that we all want to see," he told UK and Saudi personnel during the visit.
"But also a lot of work to do in relation to the Strait of Hormuz, which has an impact everywhere across the world."
British Foreign Minister Yvette Cooper said Britain will work with the shipping, insurance and energy sectors to try to restore confidence in the Strait of Hormuz "as quickly as possible" after the US-Iran ceasefire.
"Iran must cease all mining, drone attacks, and other attempts to block commercial shipping in the Strait immediately," she said in the statement.