Hormuz is not a binary switch: how we determine whether passage actually exists
Calling the strait simply “open”, “closed” or “uncertain” mixes different phenomena. A waterway may remain physically passable while traffic collapses, ships are attacked, insurers raise premiums and one party attempts to impose routes or conditions.
The four questions we answer
1. Does physical passage exist?
This is the primary variable. A commercial transit confirmed by a high-quality maritime source proves that the strait is not physically closed in an absolute sense. Political declarations never override an observed crossing on their own.
2. How much traffic is moving?
Observed flows are compared with historical references and classified as normal, reduced, severely reduced or near-halt. The difference between “some ships are moving” and “the system is operating normally” is essential.
3. Who can transit and under what conditions?
We assess controls, imposed routes, inspections, sanctions, tolls, insurance constraints and selective restrictions. Traffic may exist while access is neither free nor predictable.
4. What risk does a vessel face?
JMIC/UKMTO threat levels, confirmed attacks, mines, GNSS interference, VHF warnings and insurance conditions form an independent dimension. Severe risk does not equal physical closure, but it can profoundly degrade commercial operability.
V7 public states
- OPEN: confirmed transit and conditions close to normal.
- OPEN WITH RESTRICTIONS: confirmed passage with material restrictions or risk.
- OPEN · SEVERELY RESTRICTED TRANSIT: confirmed crossings, but flows are heavily depressed, access is conditional or risk is severe/extreme.
- EFFECTIVELY CLOSED: routine commercial traffic is almost halted and multiple independent sources confirm it, without recent crossings contradicting that conclusion.
- CLOSED: operational interruption is confirmed and, where relevant, a formal closure is supported by evidence.
- NO RECENT OPERATIONAL DATA: reserved for a genuine absence of recent evidence; it is not used merely because headlines conflict.
Evidence hierarchy
JMIC/UKMTO, IMO and maritime notices are prioritised, followed by Reuters, AP and specialist sources with traffic data, then general media. An opinion headline, a question or a political declaration cannot independently confirm opening or closure.
Core rule
If recent verifiable commercial transits exist, the system cannot call the strait physically “closed”. It may instead classify the situation as open with severely restricted transit, communicating both the reality of passage and the seriousness of the disruption.
Why this is more useful
The observatory is not trying to win a semantic argument over the word “open”. It answers the operational question that matters to operators, journalists and readers: are ships crossing, how many, under what conditions and at what risk?