The PGSA Blacklist: Iran’s Expanding Maritime Compliance Regime in the Strait of Hormuz

Iran’s Persian Gulf Strait Authority has moved beyond issuing navigational warnings and begun constructing what increasingly resembles a maritime compliance regime around the Strait of Hormuz. The original PGSA blacklist identified 45 vessels that Tehran said had violated Iranian transit requirements, with the possibility of fines, detention or cargo confiscation during subsequent passages. More significantly, Iran warned that vessels involved in ship-to-ship transfers or other commercial activity with listed ships could themselves be designated as non-compliant.¹

The importance of the blacklist therefore lies less in the number of vessels named than in the possibility that exposure can spread through commercial relationships. A vessel’s previous transit history may influence not only its own future access to the Strait, but the decisions of charterers, cargo owners, insurers and ships that subsequently interact with it.

That possibility is no longer theoretical. Reuters reported in late August that at least three Indian refiners and a major international energy company had decided to avoid vessels on Iran’s blacklist, including in ship-to-ship operations.² The threat of enforcement is therefore already beginning to affect commercial decision-making without Iran having to intercept every listed ship.

The blacklist is emerging at an unusually consequential moment. Commercial traffic through Hormuz remains heavily constrained by the wider US-Iran conflict, tanker attacks have continued around the Strait, and operators are increasingly relying on alternative routing and ship-to-ship transfers outside the Arabian/Persian Gulf. The PGSA regime is consequently developing inside an environment in which physical risk and regulatory pressure increasingly reinforce one another.

From Navigation Rules to Commercial Pressure

Iran established the Persian Gulf Strait Authority during the current conflict as part of its effort to assert greater control over movement through Hormuz. The PGSA has told cargo interests to check its list before fixing vessels and has warned that designated ships may face penalties including fines, detention and confiscation.¹

The most consequential aspect of the system is its treatment of commercial counterparties.

Argus reported that vessels involved in ship-to-ship transfers, transshipment or other operations with listed ships could also become subject to restrictions.³ Iran has also provided a mechanism under which owners may seek removal from the list, giving the system elements of designation, secondary exposure, enforcement and delisting.

This does not make the PGSA equivalent to an internationally recognised sanctions authority. Iran’s asserted control over the Strait remains contested. The International Maritime Organization Council has urged states to reject attempts to impose unilateral restrictions inconsistent with established navigation rights.⁴

But legal legitimacy and commercial effectiveness are different questions.

A shipowner does not need to recognise Iranian jurisdiction in order to conclude that ignoring the PGSA creates unacceptable operational risk. If the possibility of detention, diversion or physical interference becomes credible enough to influence voyage planning, the regime acquires practical power regardless of whether its legal claims are internationally accepted.

The Original PGSA Vessel List

Reuters reproduced the original blacklist in August as 45 vessels identified by name and IMO number.¹ Argus referred to a 46-vessel PGSA list, suggesting either a duplication or discrepancy in the original publication.³ For consistency, the table below follows the 45 unique vessels reproduced through Reuters reporting.

IMO numbers are particularly important in this context because vessel names, flags, owners and managers can change. The IMO number generally remains associated with the hull throughout its operating life, allowing designation history to be followed even if a ship is later sold, renamed or reflagged.

The list is also notable for its breadth. Reuters reported links to major Gulf and international operators including ADNOC Logistics & Services, Bahri, Navig8, Stolt Tankers, Klaveness Ship Management and Sinokor.¹ The vessels span crude, products, LNG, LPG and other specialised trades, suggesting that the PGSA regime is not confined to one segment of the Gulf energy market.

The List Is Expanding

A further 11 vessels were reported as additions to the PGSA list on 2 September, taking the nominal total to 57 entries. Because one vessel appears to have been duplicated in the original publication, the number of unique vessels may be lower.

The reported additions include four UAE-linked vessels — Tarif, Delma, El Gaia and Asphalt Alliance — four Saudi-linked tankers — Ixora, Yaqut, Zaynah and Ajwad — two Chinese-linked LPG carriers, Zixuan and Gas Marakua, and the Greek-linked Olympios Gas.

Several can already be matched confidently to IMO records, including El Gaia (IMO 9325336), Asphalt Alliance (IMO 9287883), Yaqut (IMO 9917878), Zaynah (IMO 9854703), Zixuan (IMO 9317298), Gas Marakua (IMO 9240421) and Olympios Gas (IMO 1069637).⁵

The remaining additions should be treated more cautiously until the vessel names can be matched reliably at IMO level. This is particularly important because commercial ship names are not necessarily unique, whereas an incorrect IMO attribution would associate the PGSA designation with the wrong hull.

The geographic pattern of the reported additions is nevertheless significant. UAE and Saudi-linked vessels account for most of the new names, while Chinese and Greek shipping interests are also represented. If that pattern continues, the blacklist may reveal something about how Tehran is prioritising states, trades and commercial relationships rather than simply recording isolated navigation violations.

Ship-to-Ship Transfers Create the Most Important Secondary Risk

The PGSA’s warning concerning ship-to-ship transfers may become the most commercially significant feature of the regime.

STS activity has become increasingly important because disruption through Hormuz has forced Gulf exporters and buyers to improvise. Crude and LNG cargoes are being transferred outside the Strait so that some ships do not need to complete the entire passage themselves.

Reuters reported on 2 September that three Qatari and UAE LNG cargoes had recently been transferred between vessels outside Hormuz — an unusual development for LNG shipping.⁶

Several of the vessels involved are already on the PGSA blacklist.

GasLog Shanghai completed an STS transfer with GasLog Savannah off Oman after loading in Qatar. Al Rekayyat, another listed vessel, transferred LNG to the Qatari tanker Tembek, which subsequently carried the cargo to India. ADNOC-controlled Mraweh transferred an LNG cargo to LNG Enugu off Oman before the cargo continued towards Japan.⁶

This creates a direct tension between commercial adaptation and Iranian compliance pressure.

Ship-to-ship operations provide Gulf exporters with a mechanism for maintaining energy flows when the Strait is difficult to navigate. Yet the same STS relationships are precisely the sort of commercial interaction the PGSA says may expose a counterparty to designation.

The result is potentially self-reinforcing. The more operators depend on STS activity to reduce exposure to Hormuz, the more consequential Iran’s threat to penalise STS counterparties becomes.

Commercial Behaviour Is Already Changing

There is evidence that parts of the market are taking the blacklist seriously.

Reuters reported that at least three Indian refiners and one global energy company intended to avoid blacklisted vessels because of the risk associated with their future Hormuz movements.² Some companies were also reviewing potential STS exposure.

The key point is that Iran does not need universal enforcement for the blacklist to alter trade.

Commercial compliance systems often derive much of their power from anticipated consequences. Businesses change behaviour because the expected cost of being caught is greater than the benefit of continuing as normal.

The PGSA operates through a different coercive mechanism from conventional Western sanctions, but the behavioural principle is similar.

US or European sanctions threaten access to finance, insurance, markets or the dollar system. Iran can threaten access to a physical maritime chokepoint.

One is principally financial and legal. The other can be physical and operational.

Both can affect commercial behaviour before a formal penalty is imposed.

Hormuz Is Becoming a Contested Compliance Environment

The blacklist is more significant because it is being developed inside a Strait already shaped by military confrontation.

Commercial traffic through Hormuz remains below recent norms, while the latest US-Iran exchanges have reinforced concerns over the security of Gulf energy movements. Reuters reported on 2 September that only four commodity vessels transited the Strait on Tuesday, compared with a recent ten-day average of around 13.⁷

Iranian influence is already uneven across cargo flows. Iraq increased oil exports in August after receiving Iranian permission for tankers to pass through the Strait, while other Gulf producers faced substantially greater restrictions.⁸

This is an important development because it suggests that access to Hormuz is increasingly differentiated rather than simply open or closed.

The central strategic question may therefore no longer be whether Iran can block the Strait completely.

It is whether Tehran can determine — formally or informally — which ships move, by which routes, under what conditions and with what commercial relationships attached to them.

That represents a different form of leverage.

Closing Hormuz generates enormous economic costs, including for Iran itself. Selectively regulating movement potentially gives Tehran a more calibrated instrument: allowing some cargoes to pass while increasing the cost, risk or uncertainty faced by others.

The Blacklist Extends the Geography of Coercion

The implications extend beyond Iranian territorial waters.

If a ship can acquire future Hormuz exposure through an STS transfer conducted outside the Strait, then Iranian commercial pressure can influence transactions taking place in waters off Oman or the UAE even when Iran has no immediate physical role in the operation.

That does not mean Iran has legal jurisdiction over those transactions.

It means that a later Hormuz transit can become the enforcement point.

The distinction matters.

A vessel conducting an STS operation off Oman may face no immediate Iranian interference. But if that interaction causes it to be designated and the vessel expects to transit Hormuz again in future, the earlier transaction acquires strategic significance.

In that sense, the PGSA is attempting to connect commercial behaviour outside Hormuz to future physical access through Hormuz.

That is what makes secondary exposure potentially powerful.

A Regime Built Around Movement

The PGSA blacklist should therefore be understood as part of a larger change in the contest over the Strait.

For decades, the central question surrounding Hormuz was whether Iran would close it.

The present environment is demonstrating that closure is only one possible form of control.

Movement can also be shaped through intimidation, selective permission, route requirements, physical threats, vessel designation, ship-to-ship exposure and commercial self-deterrence.

The blacklist brings those mechanisms together.

Its effectiveness will ultimately depend on enforcement. If Iran repeatedly threatens vessels but fails to act, commercial actors may become less willing to adjust their behaviour. If listed vessels are detained, diverted or otherwise penalised, the opposite may occur: designation could become a material factor in chartering and voyage planning across the Gulf shipping market.

The first signs suggest the regime is already having some effect. Companies are avoiding listed vessels, unusual STS structures are becoming more common, and Iranian permission appears to be influencing which Gulf cargoes can move through the Strait.²⁶⁸

The PGSA blacklist is therefore more than an administrative list of ships.

It is an attempt to turn control over geography into influence over commercial behaviour.

And that may ultimately be the more consequential development in Hormuz: not whether Iran can stop every vessel, but whether it can make enough of the maritime industry behave as though its permission matters.

Sources

1. Reuters, “Iran threatens 45 tankers with fines, confiscation in Hormuz escalation,” 24 August 2026.
https://www.reuters.com/world/middle-east/iran-warns-vessels-violating-hormuz-transit-rules-fines-detention-2026-08-24/

2. Reuters, “Some oil companies to avoid ships on Iran blacklist, sources say,” 26 August 2026.
https://www.reuters.com/business/energy/some-oil-companies-avoid-ships-iran-blacklist-sources-say-2026-08-26/

3. Argus Media, “Iran’s PGSA tightens Hormuz transit rules,” 24 August 2026.
https://www.argusmedia.com/en/news-and-insights/latest-market-news/2868618-iran-s-pgsa-tightens-hormuz-transit-rules

4. Reuters, “Countries must reject Iran efforts to control Hormuz, UN agency document says,” 10 July 2026.
https://www.reuters.com/world/middle-east/countries-must-reject-iran-efforts-control-hormuz-un-agency-document-says-2026-07-10/

5. Vessel identity checks using ship-register and vessel-database records for reported 2 September PGSA additions.

6. Reuters, “Qatari, UAE LNG cargoes transferred via ship-to-ship outside Strait of Hormuz,” 2 September 2026.
https://www.reuters.com/business/energy/qatari-uae-lng-cargoes-transferred-via-ship-to-ship-outside-strait-hormuz-2026-09-02/

7. Reuters, “Shipping traffic via Strait of Hormuz stays below 10-day average, data shows,” 2 September 2026.
https://www.reuters.com/business/energy/shipping-traffic-via-strait-hormuz-stays-below-10-day-average-data-shows-2026-09-02/

8. Reuters, “Iraq boosts oil exports in August as low prices draw buyers,” 2 September 2026.
https://www.reuters.com/business/energy/iraq-boosts-oil-exports-august-low-prices-draw-buyers-2026-09-02/