HighI Geo-Economics & Chokepoints28 October 2026, Wednesday

US Navy warns ships against unnecessary transits of the Strait of Hormuz

US Naval Forces Central Command (NAVCENT) issued advisory JMIC 016-26 on 28 October, asking ships with no need to pass between the Gulf of Oman and the Strait of Hormuz to stay clear of the area. A similar advisory was last issued in mid-July, when the blockade of Iranian ports began.

Location: GULF OF OMAN

According to the advisory as reported by Bloomberg on 28 October, ships that must transit should build extra time into their voyages because of rising traffic density and military blockade inspections. Gulf News says the notice was published on 28 October by the Joint Maritime Information Center (JMIC) and rated the regional threat level as "severe". The blockade applies to every vessel regardless of flag or owner and covers the Gulf, the Strait of Hormuz, the Gulf of Oman and the Arabian Sea. Even ships sailing in ballast between neutral ports can be stopped and searched, and must submit 6 categories of documents as PDFs on request.

No reason for the advisory was given; CENTCOM and NAVCENT did not answer Bloomberg's questions on 28 October. Bloomberg reports that Iranian attacks on shipping rose in October to the highest level of the war, close to 30 incidents. According to the same report, the US blockade has driven Iran's crude exports close to zero, while total Gulf flows have neared pre-war levels. Bloomberg's 28 October report adds that in recent months shuttle tankers carrying crude over short distances inside the Gulf have handled most of the strait's crude traffic. The advisory came on the same day as reports that the US is preparing a new operation against Iran after the 3 November midterms; no official link has been drawn between the two.

Talay assessment

Bottom line

The advisory does not close the strait, but it converts the cost of passage into time: every ship now carries extra transit time, paperwork and the risk of a search. Its July counterpart came at the start of the blockade, which suggests the 28 October warning may herald a new phase of inspections. The most likely path is that flows continue while delays and insurance costs stay high until early November.

Likely effects

Freight and insuranceNegativeWeeks
Extra transit time and search risk keep daily waiting costs and the war risk premium elevated for tankers leaving the Gulf.
Gulf exportsUncertainWeeks
Bloomberg says Gulf flows had neared pre-war levels; the advisory does not stop them but lengthens each voyage.
TürkiyeNegative1–6 months
As delays and insurance costs persist on Gulf crude and LPG cargoes, Türkiye's energy import bill struggles to come down.

Possibilities, ranked

1
Tighter inspections, flows continue55%
Searches and document checks increase and transits slow, but Gulf exports are largely maintained.
Watch: IMF PortWatch daily Hormuz transit counts and the next JMIC advisory
2
Preparation for an operation30%
The advisory is the maritime leg of a possible operation after 3 November; transits fall markedly in early November.
Watch: NAVCENT and UKMTO warnings after 3 November
3
Warning withdrawn15%
A diplomatic breakthrough lowers the threat level and the extra transit time requirement is dropped.
Watch: JMIC lowering the threat level from severe

Probabilities are calibrated judgement based on the sources, not measurement, and are revised as new information arrives. Not investment advice.

Market reaction

Indicators affected

Hormuz transits▼ delays
October ship attacks (Bloomberg)▼ ~30
Regional threat level (JMIC)▼ severe

Historical context