Iran seizes the tanker Stena Impero in the Strait of Hormuz
Iran seizes the tanker Stena Impero in the Strait of Hormuz. The disruption ran from 2019-07-19 (19 July 2019) to 2019-09-27 (27 September 2019), 71 days, affecting Strait of Hormuz. Strait of Hormuz averaged 46.6 transits per day during the event window against an expected 48.5 (-3.8%). Strait of Hormuz averaged 77.9 transits per day during the event window against an expected 81.2 (-4.1%).
Key facts
- Started
- 2019-07-19 (19 July 2019)
- Ended
- 2019-09-27 (27 September 2019)
- Status
- ended
- Severity
- 3 Significant
- Scope
- chokepoint
- Chokepoints
- Strait of Hormuz
- Ports
- None
- Lanes
- None
- Countries
- Iran, United Kingdom
- Confidence
- high: The seizure, its location and the shipping security level come from United Kingdom government statements, and the release date from the operator's own statements and consistent reporting.
- First reported
- 2019-07-19 (19 July 2019)
- Severity basis: A restriction at a chokepoint; after the seizure the United Kingdom raised the security level for British flagged shipping to level 3 and advised against all passage through the Strait of Hormuz.
What happened
On 2019-07-19 (19 July 2019) Iranian forces boarded and seized the British flagged product tanker Stena Impero as it passed through the Strait of Hormuz, and took the ship to Bandar Abbas with its 23 crew aboard. The United Kingdom government said the vessel was intercepted in the westbound traffic lane inside Omani territorial waters by fast boats and a helicopter of the Revolutionary Guard, and called the seizure a breach of international law. Iran said the ship had committed marine violations. On 2019-07-22 (22 July 2019) the Department for Transport raised the security level for British flagged shipping to level 3 and advised against all passage through the strait. Seven crew were released in early September, and the ship left Bandar Abbas for Dubai on 2019-09-27 (27 September 2019).
Measured effect
Transits, tankers, Strait of Hormuz
- Baseline (expected)
- 48.5 transits per day
- Observed
- 46.6 transits per day
- Change
- -1.8 (-3.8%)
- Standardised score
- -0.3
- Event window
- 2019-07-19 to 2019-09-27 (71 days)
- Baseline window
- 2019-05-17 to 2019-07-11 (56 valid days)
- Method
- wfm-effect-1.0
- Computed
- 2026-09-19 (19 September 2026), data revision 1:34a78269ac72
Source: IMF PortWatch (portwatch.imf.org), International Monetary Fund, using UN Global Platform AIS data. Statistics derived by World Freight Monitor. Terms.
This is a measured change in public data during the event window, compared with a baseline before it. It shows timing, not cause. We describe an event as causing a change only when an official source says so.
Transits, all vessel types, Strait of Hormuz
- Baseline (expected)
- 81.2 transits per day
- Observed
- 77.9 transits per day
- Change
- -3.3 (-4.1%)
- Standardised score
- -0.4
- Event window
- 2019-07-19 to 2019-09-27 (71 days)
- Baseline window
- 2019-05-17 to 2019-07-11 (56 valid days)
- Method
- wfm-effect-1.0
- Computed
- 2026-09-19 (19 September 2026), data revision 1:15b4f05ba9df
Source: IMF PortWatch (portwatch.imf.org), International Monetary Fund, using UN Global Platform AIS data. Statistics derived by World Freight Monitor. Terms.
This is a measured change in public data during the event window, compared with a baseline before it. It shows timing, not cause. We describe an event as causing a change only when an official source says so.
Timeline
- Iranian forces board the Stena Impero in the Strait of Hormuz at about 16:00 United Kingdom time and take her towards Iran. The operator reports losing contact with the ship. [s2] [s3]
- The United Kingdom government says the tanker was seized in Omani waters in contravention of international law and summons Iran's charge d'affaires in London. [s1] [s2]
- The Foreign Secretary tells Parliament that the Department for Transport has raised the security level for British flagged shipping to level 3, advising against all passage in Iranian waters and in the strait as a whole. [s2] [s5]
- The operator says seven of the crew are to be released, and reports on the following day that they have left the vessel. [s3]
- The vessel leaves Bandar Abbas and sails for Dubai, where the remaining crew disembark for medical checks. [s3] [s4]
Cause
Iran said the tanker was held for marine violations, reported to include switching off its tracking equipment and a collision with a fishing vessel. The United Kingdom government rejected that account and said the seizure was unlawful and came after the detention of an Iranian tanker off Gibraltar earlier in July 2019. Attributed by: Government of Iran; United Kingdom government. [s2] [s4]
Resolution
Corrections
No corrections to this record as of 2026-09-16 (16 September 2026).
Sources
- [s1] Foreign and Commonwealth Office, Iran tanker seizure: UK government response, published 2019-07-21 (21 July 2019), accessed 2026-09-15. Archived copy. (official)
- [s2] Foreign and Commonwealth Office, Situation in the Gulf: Foreign Secretary statement, published 2019-07-22 (22 July 2019), accessed 2026-09-15. Archived copy. (official)
- [s3] Stena Bulk, Statements archive, accessed 2026-09-15. Archived copy. (official)
- [s4] Al Jazeera, Seized UK-flagged tanker Stena Impero leaves Iranian port, published 2019-09-27 (27 September 2019), accessed 2026-09-15. Archived copy. (press)
- [s5] The Maritime Executive, UK Asks British Ships to Avoid Strait of Hormuz, published 2019-07-22 (22 July 2019), accessed 2026-09-15. Archived copy. (press)