Iran's Strait of Hormuz Mine Laying: A Threat to Global Shipping

Iran has deployed small surface vessels to lay mines in parts of the Strait of Hormuz, a critical waterway for global shipping. The exact number of mines laid is unknown, but Iran has left a path open to ships that are prepared to pay a toll.

According to US officials, Iran has indicated that it cannot locate all of the mines that it has laid and lacks the capability to remove them. The mines are part of an array of offensive options available to Iran in the strait, including cheap drones, anti-ship missiles, and fast-attack small vessels.

Iran is thought to have deployed two main types of mine: the Maham 3 and the Maham 7. The Maham 3 is an anchored, 300kg mine that can be used in waters as deep as 100 meters, while the Maham 7 is a bottom-resting 220kg mine for use in shallower waters.

The US plans to use uncrewed marine mine-hunting vehicles, such as the Knifefish undersea mine hunter, to clear the mines. The US could also deploy the AN/ASQ-235 (Archerfish) airborne mine neutralization system from an MH 60S helicopter.

The global economy's reliance on maritime trade gives countries deploying mines an outsized leverage compared with the relatively low cost of laying the mines. It takes only a small number of mines to close sea lanes, not least because some mines can be set to detonate after a certain number of ships have passed over, creating uncertainty.