Iran seizes the tanker Stena Impero in the Strait of Hormuz

Name: Measured effect: Iran seizes the tanker Stena Impero in the Strait of Hormuz
Creator: World Freight Monitor
License: https://creativecommons.org/licenses/by/4.0/

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 77.9 transits per day during the event window against an expected 81.2 (-4.1%). Strait of Hormuz averaged 46.6 transits per day during the event window against an expected 48.5 (-3.8%).

Key facts

Started: 2019-07-19 (19 July 2019)
Ended: 2019-09-27 (27 September 2019)
Status: ended
Type: Security incident
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

Transits, tankers, Strait of Hormuz, 2019-05-10 (10 May 2019) to 2019-11-08 (8 November 2019): values ranged from 28 transits per day on 2019-05-14 to 69 transits per day on 2019-06-16, with a mean of 47.0 transits per day. The latest value, for 2019-11-08, was 48 transits per day. The shaded band marks the event window, 2019-07-19 to 2019-09-27.

Source: IMF PortWatch (portwatch.imf.org), International Monetary Fund, using UN Global Platform AIS data. Statistics derived by World Freight Monitor. Terms. Retrieved 2026-11-10 (10 November 2026).

Transits, tankers, Strait of Hormuz (transits per day).
Date	transits per day
2019-05-10	40
2019-05-11	50
2019-05-12	57
2019-05-13	47
2019-05-14	28
2019-05-15	47
2019-05-16	58
2019-05-17	47
2019-05-18	51
2019-05-19	42
2019-05-20	48
2019-05-21	35
2019-05-22	35
2019-05-23	43
2019-05-24	42
2019-05-25	52
2019-05-26	54
2019-05-27	53
2019-05-28	43
2019-05-29	50
2019-05-30	58
2019-05-31	49
2019-06-01	36
2019-06-02	50
2019-06-03	55
2019-06-04	60
2019-06-05	53
2019-06-06	38
2019-06-07	44
2019-06-08	46
2019-06-09	45
2019-06-10	57
2019-06-11	47
2019-06-12	46
2019-06-13	41
2019-06-14	45
2019-06-15	49
2019-06-16	69
2019-06-17	47
2019-06-18	43
2019-06-19	51
2019-06-20	45
2019-06-21	42
2019-06-22	50
2019-06-23	43
2019-06-24	69
2019-06-25	63
2019-06-26	51
2019-06-27	51
2019-06-28	45
2019-06-29	57
2019-06-30	53
2019-07-01	56
2019-07-02	37
2019-07-03	65
2019-07-04	48
2019-07-05	62
2019-07-06	59
2019-07-07	46
2019-07-08	46
2019-07-09	56
2019-07-10	42
2019-07-11	50
2019-07-12	57
2019-07-13	57
2019-07-14	40
2019-07-15	46
2019-07-16	47
2019-07-17	47
2019-07-18	40
2019-07-19	44
2019-07-20	39
2019-07-21	54
2019-07-22	46
2019-07-23	47
2019-07-24	47
2019-07-25	53
2019-07-26	44
2019-07-27	38
2019-07-28	46
2019-07-29	45
2019-07-30	43
2019-07-31	42
2019-08-01	54
2019-08-02	48
2019-08-03	55
2019-08-04	59
2019-08-05	42
2019-08-06	52
2019-08-07	53
2019-08-08	53
2019-08-09	43
2019-08-10	58
2019-08-11	39
2019-08-12	45
2019-08-13	50
2019-08-14	50
2019-08-15	39
2019-08-16	46
2019-08-17	50
2019-08-18	55
2019-08-19	48
2019-08-20	35
2019-08-21	57
2019-08-22	40
2019-08-23	41
2019-08-24	46
2019-08-25	44
2019-08-26	54
2019-08-27	44
2019-08-28	46
2019-08-29	52
2019-08-30	51
2019-08-31	42
2019-09-01	41
2019-09-02	47
2019-09-03	32
2019-09-04	44
2019-09-05	49
2019-09-06	52
2019-09-07	46
2019-09-08	36
2019-09-09	52
2019-09-10	42
2019-09-11	43
2019-09-12	53
2019-09-13	51
2019-09-14	53
2019-09-15	38
2019-09-16	47
2019-09-17	44
2019-09-18	63
2019-09-19	47
2019-09-20	47
2019-09-21	47
2019-09-22	41
2019-09-23	43
2019-09-24	43
2019-09-25	33
2019-09-26	49
2019-09-27	47
2019-09-28	47
2019-09-29	59
2019-09-30	49
2019-10-01	51
2019-10-02	40
2019-10-03	34
2019-10-04	37
2019-10-05	44
2019-10-06	35
2019-10-07	44
2019-10-08	35
2019-10-09	42
2019-10-10	45
2019-10-11	49
2019-10-12	32
2019-10-13	45
2019-10-14	50
2019-10-15	59
2019-10-16	57
2019-10-17	62
2019-10-18	37
2019-10-19	50
2019-10-20	49
2019-10-21	45
2019-10-22	37
2019-10-23	45
2019-10-24	54
2019-10-25	43
2019-10-26	55
2019-10-27	36
2019-10-28	43
2019-10-29	42
2019-10-30	60
2019-10-31	39
2019-11-01	43
2019-11-02	40
2019-11-03	31
2019-11-04	40
2019-11-05	33
2019-11-06	38
2019-11-07	39
2019-11-08	48

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

Transits, all vessel types, Strait of Hormuz, 2019-05-10 (10 May 2019) to 2019-11-08 (8 November 2019): values ranged from 49 transits per day on 2019-10-04 to 103 transits per day on 2019-07-06, with a mean of 77.9 transits per day. The latest value, for 2019-11-08, was 77 transits per day. The shaded band marks the event window, 2019-07-19 to 2019-09-27.

Source: IMF PortWatch (portwatch.imf.org), International Monetary Fund, using UN Global Platform AIS data. Statistics derived by World Freight Monitor. Terms. Retrieved 2026-11-10 (10 November 2026).

Transits, all vessel types, Strait of Hormuz (transits per day).
Date	transits per day
2019-05-10	60
2019-05-11	81
2019-05-12	85
2019-05-13	76
2019-05-14	58
2019-05-15	70
2019-05-16	82
2019-05-17	88
2019-05-18	84
2019-05-19	64
2019-05-20	77
2019-05-21	55
2019-05-22	59
2019-05-23	66
2019-05-24	75
2019-05-25	86
2019-05-26	80
2019-05-27	85
2019-05-28	75
2019-05-29	89
2019-05-30	90
2019-05-31	82
2019-06-01	56
2019-06-02	79
2019-06-03	84
2019-06-04	93
2019-06-05	85
2019-06-06	73
2019-06-07	77
2019-06-08	84
2019-06-09	75
2019-06-10	97
2019-06-11	81
2019-06-12	67
2019-06-13	65
2019-06-14	80
2019-06-15	85
2019-06-16	97
2019-06-17	74
2019-06-18	75
2019-06-19	81
2019-06-20	77
2019-06-21	77
2019-06-22	86
2019-06-23	70
2019-06-24	102
2019-06-25	93
2019-06-26	81
2019-06-27	86
2019-06-28	79
2019-06-29	84
2019-06-30	99
2019-07-01	90
2019-07-02	73
2019-07-03	102
2019-07-04	99
2019-07-05	102
2019-07-06	103
2019-07-07	86
2019-07-08	79
2019-07-09	91
2019-07-10	75
2019-07-11	86
2019-07-12	96
2019-07-13	91
2019-07-14	77
2019-07-15	87
2019-07-16	77
2019-07-17	76
2019-07-18	69
2019-07-19	70
2019-07-20	80
2019-07-21	87
2019-07-22	83
2019-07-23	71
2019-07-24	67
2019-07-25	90
2019-07-26	73
2019-07-27	61
2019-07-28	74
2019-07-29	82
2019-07-30	76
2019-07-31	74
2019-08-01	84
2019-08-02	84
2019-08-03	89
2019-08-04	93
2019-08-05	65
2019-08-06	86
2019-08-07	93
2019-08-08	84
2019-08-09	79
2019-08-10	88
2019-08-11	76
2019-08-12	78
2019-08-13	75
2019-08-14	79
2019-08-15	73
2019-08-16	68
2019-08-17	80
2019-08-18	86
2019-08-19	80
2019-08-20	59
2019-08-21	87
2019-08-22	64
2019-08-23	75
2019-08-24	83
2019-08-25	80
2019-08-26	85
2019-08-27	77
2019-08-28	68
2019-08-29	88
2019-08-30	82
2019-08-31	64
2019-09-01	76
2019-09-02	81
2019-09-03	63
2019-09-04	81
2019-09-05	81
2019-09-06	84
2019-09-07	78
2019-09-08	72
2019-09-09	74
2019-09-10	78
2019-09-11	72
2019-09-12	81
2019-09-13	81
2019-09-14	97
2019-09-15	67
2019-09-16	89
2019-09-17	75
2019-09-18	85
2019-09-19	73
2019-09-20	81
2019-09-21	82
2019-09-22	71
2019-09-23	78
2019-09-24	76
2019-09-25	58
2019-09-26	80
2019-09-27	74
2019-09-28	85
2019-09-29	97
2019-09-30	74
2019-10-01	79
2019-10-02	69
2019-10-03	56
2019-10-04	49
2019-10-05	75
2019-10-06	61
2019-10-07	64
2019-10-08	60
2019-10-09	68
2019-10-10	69
2019-10-11	66
2019-10-12	68
2019-10-13	69
2019-10-14	86
2019-10-15	98
2019-10-16	89
2019-10-17	94
2019-10-18	67
2019-10-19	79
2019-10-20	89
2019-10-21	74
2019-10-22	66
2019-10-23	75
2019-10-24	88
2019-10-25	71
2019-10-26	90
2019-10-27	67
2019-10-28	76
2019-10-29	64
2019-10-30	90
2019-10-31	62
2019-11-01	69
2019-11-02	67
2019-11-03	50
2019-11-04	64
2019-11-05	69
2019-11-06	58
2019-11-07	69
2019-11-08	77

Replay

Transits, tankers, Strait of Hormuz, 2019-05-20 (20 May 2019) to 2019-09-27 (27 September 2019): values ranged from 32 transits per day on 2019-09-03 to 69 transits per day on 2019-06-16. The shaded band marks the event window, 2019-07-19 to 2019-09-27.

Source: IMF PortWatch (portwatch.imf.org), International Monetary Fund, using UN Global Platform AIS data. Statistics derived by World Freight Monitor. Terms. Retrieved 2026-11-10 (10 November 2026).

Transits, tankers, Strait of Hormuz (transits per day), daily values shown in the replay.
Date	transits per day
2019-05-20	48
2019-05-21	35
2019-05-22	35
2019-05-23	43
2019-05-24	42
2019-05-25	52
2019-05-26	54
2019-05-27	53
2019-05-28	43
2019-05-29	50
2019-05-30	58
2019-05-31	49
2019-06-01	36
2019-06-02	50
2019-06-03	55
2019-06-04	60
2019-06-05	53
2019-06-06	38
2019-06-07	44
2019-06-08	46
2019-06-09	45
2019-06-10	57
2019-06-11	47
2019-06-12	46
2019-06-13	41
2019-06-14	45
2019-06-15	49
2019-06-16	69
2019-06-17	47
2019-06-18	43
2019-06-19	51
2019-06-20	45
2019-06-21	42
2019-06-22	50
2019-06-23	43
2019-06-24	69
2019-06-25	63
2019-06-26	51
2019-06-27	51
2019-06-28	45
2019-06-29	57
2019-06-30	53
2019-07-01	56
2019-07-02	37
2019-07-03	65
2019-07-04	48
2019-07-05	62
2019-07-06	59
2019-07-07	46
2019-07-08	46
2019-07-09	56
2019-07-10	42
2019-07-11	50
2019-07-12	57
2019-07-13	57
2019-07-14	40
2019-07-15	46
2019-07-16	47
2019-07-17	47
2019-07-18	40
2019-07-19	44
2019-07-20	39
2019-07-21	54
2019-07-22	46
2019-07-23	47
2019-07-24	47
2019-07-25	53
2019-07-26	44
2019-07-27	38
2019-07-28	46
2019-07-29	45
2019-07-30	43
2019-07-31	42
2019-08-01	54
2019-08-02	48
2019-08-03	55
2019-08-04	59
2019-08-05	42
2019-08-06	52
2019-08-07	53
2019-08-08	53
2019-08-09	43
2019-08-10	58
2019-08-11	39
2019-08-12	45
2019-08-13	50
2019-08-14	50
2019-08-15	39
2019-08-16	46
2019-08-17	50
2019-08-18	55
2019-08-19	48
2019-08-20	35
2019-08-21	57
2019-08-22	40
2019-08-23	41
2019-08-24	46
2019-08-25	44
2019-08-26	54
2019-08-27	44
2019-08-28	46
2019-08-29	52
2019-08-30	51
2019-08-31	42
2019-09-01	41
2019-09-02	47
2019-09-03	32
2019-09-04	44
2019-09-05	49
2019-09-06	52
2019-09-07	46
2019-09-08	36
2019-09-09	52
2019-09-10	42
2019-09-11	43
2019-09-12	53
2019-09-13	51
2019-09-14	53
2019-09-15	38
2019-09-16	47
2019-09-17	44
2019-09-18	63
2019-09-19	47
2019-09-20	47
2019-09-21	47
2019-09-22	41
2019-09-23	43
2019-09-24	43
2019-09-25	33
2019-09-26	49
2019-09-27	47

Timeline

2019-07-19Iranian 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]
2019-07-21The 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]
2019-07-22The 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]
2019-09-04The operator says seven of the crew are to be released, and reports on the following day that they have left the vessel. [s3]
2019-09-27The 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

2019-09-27 (27 September 2019): Iran released the ship after about ten weeks. The operator said the vessel had left Iranian waters and reached Dubai, where the crew disembarked. [s3] [s4]

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)

Cite this record

The address of this record is permanent and a correction is always logged on this page, so a citation names the version you read. Add the date you accessed it.

Plain text

World Freight Monitor. "Iran seizes the tanker Stena Impero in the Strait of Hormuz." Last updated 2026-09-16 (16 September 2026). https://worldfreightmonitor.com/events/2019/tanker-seizure-strait-of-hormuz-2019/

APA

World Freight Monitor. (2026). Iran seizes the tanker Stena Impero in the Strait of Hormuz. World Freight Monitor. https://worldfreightmonitor.com/events/2019/tanker-seizure-strait-of-hormuz-2019/

BibTeX

@misc{wfm_tanker_seizure_strait_of_hormuz_2019,
  author = {{World Freight Monitor}},
  title = {Iran seizes the tanker Stena Impero in the Strait of Hormuz},
  year = {2026},
  note = {Last updated 2026-09-16},
  url = {https://worldfreightmonitor.com/events/2019/tanker-seizure-strait-of-hormuz-2019/}
}

Iran seizes the tanker Stena Impero in the Strait of Hormuz

Key facts

What happened

Measured effect

Transits, tankers, Strait of Hormuz

Transits, all vessel types, Strait of Hormuz

Replay

Timeline

Cause

Resolution

Corrections

Sources

Cite this record

Plain text

APA

BibTeX

Related events and places