Shelley said recent tanker movements show Iran-related shipments have clearly increased since the blockade was lifted. The Treasury licence gives traders and shipping operators a defined window in which certain Iranian oil-related sales can proceed without breaching US rules.
That matters because the Strait of Hormuz is one of the world’s most important energy chokepoints. Even small shifts in transit patterns can affect insurance, freight rates, and whether shipowners are willing to enter the Gulf. None of that is glamorous, but it is usually where the real consequences show up first.
Normal shipping has also picked up
The increase has not been limited to Iran-linked tankers. Martin Kelly of crisis management firm EOS Risk Group said there had also been a rise in ordinary commercial traffic.
"That said, there has been an increase in 'normal' trade too," Kelly said.
On Monday, four liquefied natural gas tankers appeared on ship-tracking platforms heading through the strait toward Qatar’s Ras Laffan port. On Tuesday, at least three tankers and three cargo vessels sailed out of the Gulf.
Those numbers suggest some operators are more confident, but only up to a point. The shipping picture remains mixed: more vessels are moving, but many are still waiting.
Ship-tracking data shows that more than 250 tankers and 440 cargo ships remain inside the Gulf, based on their last reported positions. More than 80% of those tankers are stationary or at anchor, and roughly one in six appears to be carrying cargo.
That is not what a full reopening looks like. It is closer to a cautious restart, with owners, charterers, insurers, and governments all watching the same maps and pretending they are less nervous than they are.
Why are ships using different routes?
The route is now a central issue. Recent movements have mostly followed the northern passage through Iranian waters, which Iran has approved. That differs from the southern route, closer to the coast of Oman, recommended by maritime authorities linked to the United States and its partners.
The Joint Maritime Information Center, a multinational maritime group that includes the US, has warned vessels to avoid the central part of the strait "due to the existence of mines".
So far, the centre has issued warnings and co-ordinates for two mines. It has also said that "active mine clearance operations are ongoing".
The centre’s advice is for vessels to use a narrower southern corridor through the strait, near Oman, which it says "has been confirmed clear of mines".
Those recommendations put ship operators in a practical bind. The Iranian-approved northern route may be politically safer for vessels engaging with Iran, while the southern route is the one being described by JMIC as cleared of mines. For captains and insurers, that is not exactly a relaxing menu.
Mine warnings are still limiting traffic
Concerns over mines in internationally recognised lanes through the middle of the Strait of Hormuz have helped keep shipping below pre-war levels.
Shelley said tanker movements along the southern corridor had resumed late last week, before stalling again after Iran declared the strait closed on Saturday 20 June.
"We saw tankers passing along the southern corridor at the end of last week and then when Iran declared the strait closed again on Saturday 20 June the transits stalled," she said.
"There has been some resumption of tankers passing today but still only a trickle," she added.
By Tuesday, ship-tracking data showed at least four tankers apparently using the southern route through the strait. They included a Norway-flagged vessel bound for Singapore and a Liberia-flagged tanker heading to Taiwan.
The result is a shipping lane that is technically open, but still hemmed in by caution, official warnings, route approvals, and mine-clearance updates. The deal has moved vessels. It has not removed the risk calculation.
