Iran's Multi-Faceted Blockade of the Strait of Hormuz
The Strait of Hormuz, a narrow waterway critical for global oil transport, has been effectively closed by Iran through a combination of advanced military tactics and psychological warfare. With 20% of the world's oil supplies passing through this route, the blockade has triggered market chaos and soaring prices, impacting at least 16 ships and trapping around 3,000 vessels with 20,000 crew members, according to the International Maritime Organisation.
Sea Drones: A New Threat in the Persian Gulf
Sea drones, or unmanned surface vehicles (USVs), have emerged as a key tool in Iran's arsenal, mirroring tactics seen in the war in Ukraine. These small, unmanned vessels operate on or below the water's surface, making them difficult to detect and defend against, especially during nighttime operations. In January last year, footage released by Iran's Islamic Revolutionary Guard Corps purportedly showed such craft in an underground tunnel, highlighting their covert deployment capabilities.
Naval drones laden with explosives have been used in at least two attacks on oil tankers since the conflict began. On 1 March, a crude oil tanker was hit 44 miles off the coast of Oman, resulting in one crew member's death. Days later, the Bahamas-flagged crude oil tanker Sonangol Namibe was attacked near Iraq's Khor al Zubair port, with video evidence showing a naval drone slamming into the ship and causing a massive explosion.
Sky News' data and forensics team reports that Iran has attacked at least 16 vessels around the Strait of Hormuz and the wider Gulf, with six ships struck in a single intense period early Wednesday. Iran has also suffered significant casualties, with 87 deaths reported after the US sunk an Iranian warship off the coast of Sri Lanka last week.
Midget Submarines and Anti-Ship Mines
The possibility of Iran deploying anti-ship mines in the Strait of Hormuz has gained increasing attention as the war continues. These weapons, infamous from their use in World War II minefields, pose a grave threat to ships in contested waters. Iran possesses "contact mines," but a more sophisticated danger comes from mines that lie on the seabed, releasing torpedo-like charges when sensors detect a vessel passing above.
These mines could be laid by ships, which are vulnerable to US-Israeli strikes, or by "midget submarines" based on a North Korean model, used for clandestine operations. Dr Sidharth Kaushal from the RUSI thinktank cited American sources suggesting "a small number - dozens so far" of mines have been deployed, with Reuters reporting about a dozen mines placed, most with known locations.
Anti-Ship Missiles and Strategic Reserves
Iran has largely withheld its arsenal of anti-ship missiles, such as the Iranian variant of the Chinese C802 ballistic missile or the home-produced Kheibar Shekan missile. Dr Kaushal notes that Iran has "kind of achieved their strategic aim for now" by effectively closing the Strait of Hormuz. However, this could change if commercial vessels attempt to pass through with naval escorts, making these capabilities more relevant.
The US has refused daily requests from the shipping industry for military escorts through the strait, citing the high risk of attacks, according to Reuters sources.
GPS Jamming and Electronic Warfare
GPS jamming, or interference with global navigation satellite systems (GNSS), has become a significant issue in the Strait of Hormuz, affecting both ships and aircraft. While Iran is a primary source, neighbouring countries like Oman and the UAE may also be using the technology as a defence measure against drone attacks. Dr Ramsey Faragher, director of the Royal Institute of Navigation, describes disrupting navigation signals as one of the "cheapest and effective first lines of defence" against drones.
Maps of GPS jamming show hotspots over Oman and the UAE, with tracking services like VesselFinder displaying clusters of ships in geometric patterns due to interference, not their actual positions. This electronic warfare impacts all aircraft flying near the region, compounding the disruption caused by Iran's blockade.
In summary, Iran's blockade of the Strait of Hormuz utilises a range of tools from sea drones and midget submarines to GPS jamming, creating a complex threat environment that has halted crucial oil shipments and escalated regional tensions.
