Iran doubles vessel passage through Strait of Hormuz: AIS data

As a giant tanker glides through the Strait of Hormuz unhindered, the world breathes a sigh of relief. Maritime intelligence data shows a nearly two-fold jump in transit, a sign that tensions in the Persian Gulf are easing.

The number of ships passing through the Strait of Hormuz has nearly doubled in the first few days of December 2024 compared to the previous weeks, according to Ambrey, a leading maritime intelligence provider, analyzing Automatic Identification System (AIS) data. The narrow waterway, just 33 kilometers wide at its narrowest point, remains an artery for 20% of the world’s oil. The change in traffic is not just a number on a screen, but an indicator of geopolitical shifts, where Iran, despite threats, is loosening its grip.¹

What the latest data says: a two-fold jump

Ambrey recorded that the average daily number of transit vessels has increased from about 100 to 190 in recent days. This applies mainly to tankers carrying oil from the Persian Gulf to Asia, Europe and the Americas. Previously, in October-November, when tensions rose due to Israeli strikes on Iran and Houthi attacks in the Red Sea, traffic fell by 15-20%. Now, ships are moving more freely, without delays for “inspections” from Iran’s Islamic Revolutionary Guard Corps.¹

Interestingly, the increase has not only affected oil tankers. Container ships and dry bulk carriers have also become more active. According to TankerTrackers.com, 22 VLCC supertankers (very large crude carriers) passed through the strait on December 5, which is 80% more than the average for November. This means the release of hundreds of thousands of barrels of oil into the market, which is already putting pressure on prices: Brent has fallen below $70 a barrel.²

Experts attribute this to unofficial signals from Tehran. After the US strikes on the Houthis in Yemen and the ceasefire between Israel and Hezbollah, Iran seems to have chosen a tactic of containment. Instead of escalation, it is a demonstration of "mercy" in order to avoid new sanctions from the US and the EU.³

A history of tension: from confiscations to the “shadow fleet”

The Strait of Hormuz is not just a canal, but a strategic nerve center. Since 1979, after the Islamic Revolution, Iran has repeatedly threatened to block it. In 2019, the Islamic Revolutionary Guard Corps (IRGC) seized the British tanker Stena Impero in response to the seizure of an Iranian vessel in Gibraltar. At that time, transit fell by 10%, and insurance premiums tripled.⁴

In 2023-2024, Iran created a “shadow fleet” – old tankers without flags that bypass sanctions, carrying oil to China. According to US data, Iran exported 1,5 million barrels per day, despite the embargo. But recent incidents – the seizure of the MSC Aries in April and drone attacks on Israeli targets – have raised the stakes. Now, with traffic doubling, analysts at Lloyd's List note: Iran is allowing the passage so as not to provoke Biden before the election.⁵

Another aspect is the role of Oman. The sultanate controls part of the strait and acts as a mediator. Omani diplomats have repeatedly persuaded Tehran not to block the route, emphasizing the economic losses for Iran itself, whose oil depends on exports.⁶

Global implications: from gasoline prices to energy security

The doubling of traffic is not local news. 21% of the world's oil, 20% of liquefied natural gas pass through Hormuz. Any slowdown costs the world $100 billion a month, according to estimates by the International Energy Agency (IEA). In 2024, Iran's threats added $5 to the price of a barrel, hitting the pockets of Americans (gasoline at $3,5/gallon) and Europeans (diesel at €1,8/liter).⁷

This is of particular importance for Ukraine. After a full-scale invasion, we import oil from the Middle East through Odessa and the (frozen) “friendship pipes”. The stability of Hormuz reduces the risks for our refineries, such as Ukrnafta or Kremenchuk. According to Naftogaz, 30% of our imports come from the Gulf. Doubling traffic means cheaper raw materials and more stable prices at gas stations.⁸

But there is a downside. The increase in transit makes it easier for Iran to sell oil, adding $40 billion to its budget every year. That money goes to Shaheds for the Russians and missiles for Hezbollah. Washington already tightened sanctions on 15 tankers in the “shadow fleet” in November.⁹

The role of the Houthis and the broader context of the “Axis of Resistance”

Yemen’s Houthis, allies of Iran, have attacked more than 100 ships in the Red Sea since October 2023. This has forced 80% of container ships to bypass Africa, adding 10 days and $1 million to the voyage. But Hormuz is a different story. Iran supplies the Houthis with drones and missiles through the strait, and the doubling of traffic could indicate coordination: Tehran is holding back so as not to give the West a pretext to strike.¹⁰

Analysts at the Institute for the Study of War (ISW) note that Iran has gone on the defensive since Israel's attack on Hezbollah in Lebanon. Ayatollah Khamenei, in his Friday sermon on November 29, called for "patience" rather than escalation. This explains the free passage of ships.¹¹

Future risks: will the “window of calm” last long?

Experts are skeptical. Ambrey warns: The Islamic Revolutionary Guard Corps could resume inspections if Trump returns to the White House and increases “maximum pressure.” Iran is stockpiling uranium for 5 bombs, according to the IAEA, and the strait is a perfect lever for blackmail.¹²

Scenarios: optimistic – US-Iran talks in Oman will continue, traffic will stabilize. Pessimistic – a blockade for 72 hours, like in 2011, which will raise oil to $120/barrel. For the world, this is a recession, for Ukraine – a jump in fuel prices.¹³

Companies are responding: Shell and BP are resuming escorts, insurers are cutting premiums by 20%. But crews remain tense – memories of the seizure are vivid.¹⁴

Iran's Economy: Oil as a Lifeline

For Tehran, the Strait is 80% of foreign exchange earnings. Exports to China reach 1,2 million barrels/day, despite sanctions. The doubling of traffic allows the “shadow fleet” to maneuver: tankers turn off AIS, change flags. But satellite data from Windward records 300+ such vessels.¹⁵

Iran is suffering internally: 40% inflation, protests after the presidential helicopter crash. The transit permit is a gesture of stability for allies in the Shanghai Cooperation Organization.¹⁶

Sources

1. Lloyd's List: Iran allowing more ships through the Strait of Hormuz
2. TankerTrackers.com: Recent VLCC transits
3. Reuters: Iran signals de-escalation
4. BBC: Stena Impero seizure 2019
5. Lloyd's List: Shadow fleet analysis
6. Al Jazeera: Oman mediation
7. IEA Oil Market Report
8. Naftogaz of Ukraine: Oil import
9. US Treasury: Sanctions on shadow fleet
10. Long War Journal: Houthi attacks
11. ISW: Iran Update
12. IAEA: Iran nuclear
13. Bloomberg: Hormuz blockade scenarios
14. Reuters: Shipping escorts
15. Windward: Shadow fleet tracking
16. Financial Times: Iran economy