Thomas Copeland,

Shruti Menonand

Barbara Metzler,BBC Verify

When President Donald Trump announced the US deal with Iran on Sunday and declared the "opening" of the Strait of Hormuz, his Truth Social post ended with the words - "Ships of the World, start your engines. Let the oil flow!".

BBC Verify analysis of MarineTraffic ship-tracking data, however, shows that just seven vessels appear to have passed through the critical waterway since the deal was announced and as many as 580 ships appear to be waiting in the Gulf.

Tehran effectively closed the Strait of Hormuz, through which about a fifth of the world's oil and gas supplies are usually transported, following US and Israeli strikes on 28 February.

Experts say there are significant obstacles preventing traffic from returning to the levels seen before the conflict began – security, mines and tolls.

Ship-tracking data from MarineTraffic on Tuesday shows there are more than 250 tankers and more than 330 cargo ships inside the Gulf.

About 75% of the tankers are stationary, the data suggests. Satellite imagery shows that many are gathered near major oil export terminals in Saudi Arabia, Iraq and the UAE.

The total number of vessels in the area is likely to be higher as many ships are not broadcasting their location and do not appear in MarineTraffic's data.

"The first thing we would probably see when traffic picks up through the strait is an exodus of the vessels that are trapped inside the Gulf," said Naveen Das, senior oil analyst at trade analytics firm Kpler.

But so far, that does not appear to be happening.

Security and safety

"It would take an extremely brave captain to transit through the Strait of Hormuz, given the current state," Martin Kelly of crisis management firm EOS Risk Group told BBC Verify.

Since Iran began effectively blocking the Strait of Hormuz in late February, it has fired on ships attempting to make the crossing without its permission.

The US imposed its own naval blockade of Iranian ports on 13 April and has since disabled nine "non-compliant vessels", including launching Hellfire missiles into the engine rooms of some ships, according to US Central Command.

Despite Trump announcing on Sunday the "immediate removal" of the US naval blockade, the president later said it would remain in place until the deal with Iran is signed.

Satellite images from 15 June show four US warships close to the American blockade line at the entrance to the Gulf of Oman.

After the deal's announcement, experts say ship captains, owners and insurers are preparing and positioning their vessels in the Gulf to make the journey out into the Arabian Sea - but few of them want to make the first move.

"What we've been seeing is still very much a wait-and-see mentality. No-one really wants to be the first to take that risk," said Das.

"Some of the owners and captains that are more happy with risk, like certain Greek companies, we may see them coming in and exiting successfully and that might build up confidence in others," he said.

Many captains will remember events from early April when Iran's foreign minister declared the strait was fully open, said Michelle Wiese Bockman, senior analyst at Windward Maritime Intelligence.

Just one day later, Iranian authorities said the strait was closed and more than 33 vessels were forced to reverse course mid-transit while several reported being fired on, Bockman said.

"We need to wait a couple of days, maybe until Friday, to see what this looks like," said Martin Kelly.

Mine threat

Iran threatened early in the conflict that if its coastline or islands were attacked, it would place "various types of sea mines, including floating mines that can be released from the coast" in the Gulf, according to Iran's semi-official Fars news agency.

Both the multinational Joint Maritime Information Center and Oman's Maritime Security Centre have since issued warnings about "floating" objects suspected to be mines and US Secretary of State Marco Rubio told a Senate committee that Iran had "mined large segments of Hormuz".

The removal of these mines is an essential first step to returning maritime traffic to pre-war levels, Arsenio Dominguez, secretary general of the International Maritime Organization, told the BBC.

Experts say clearing the strait of mines will be a slow process which could take anywhere from 30 days to as long as six months.

"We simply do not know and this lack of clarity is very concerning," said Phillip Belcher from the International Association of Independent Tanker Owners.

Experts say the southern route, close to Oman, appears to be largely clear of mines and the main route through the strait will be the focus of mine-hunting efforts.

"They have to go at really slow speeds, probably two or three knots, so they can conduct a survey of the underwater environments," said Kelly.

The minesweepers will then need to clear a wide enough channel for maritime traffic to move in and out of the strait at the time time, experts say.

The UK and France have despatched naval vessels to the region in anticipation of a potential mine-clearing operation in the Strait of Hormuz

Prime Minister Sir Keir Starmer pledged on Tuesday that the UK will play its "full part" in getting the Strait of Hormuz reopened "as soon as possible".

The British naval support ship RFA Lyme Bay - which has been equipped with mine-hunting kit - was seen on ship-tracking yesterday off RAF Akrotiri air base in Cyprus.

Tolls or fees

As a natural waterway through the territorial waters of Iran and Oman, vessels have historically been free to pass through the Strait of Hormuz without payment.

While neither the US nor Iran are party to the United Nations Convention on the Law of the Sea, which commits countries to allow safe passage through their waters, experts say the US position is that free passage through the Strait of Hormuz is part of customary international law.

Some man-made canals such as Panama and Suez do charge tolls and fees for specific services.

During this conflict Iran has sought to assert its sovereignty over the strait, including by establishing the "Persian Gulf Strait Authority" which it said would manage "safe passage permits".

The US and its Gulf allies have repeatedly rejected Iranian attempts to assert control over the strait.

When he announced the deal with Iran on Sunday, Trump said the strait would be opening "toll free".

Iran's Fars news agency has reported that under the new deal with the US the strait would ultimately be managed by Iran in co-ordination with Oman, including possible "service fees" for ships to transit the waterway. It is unclear what services such a fee would pay for.

Any new payment system for using the strait would "add another spanner into the works" which may add a "logistical limit or a chokehold" on how many ships can pass through each day, said Das.

"Who is enforcing it? How will it be enforced? How will fees get collected? What do other Gulf countries feel about that?" Das added.

Many of these questions may be answered during the negotiation period between Iran and the US after Friday's deal is signed, but experts say it is unlikely that Tehran will allow ships to pass through the Strait of Hormuz as freely as it did before the conflict began.

"The key point is that the strait may reopen quickly from a political or security perspective, but the commercial shipping system is likely to normalise gradually," said Dimitris Ampatzidis from Kpler.

Additional reporting by Shayan Sardarizadeh, Alex Murray and Joshua Cheetham