Iran is “choking” one of the world’s most important maritime trade routes – the Strait of Hormuz – by threatening merchant ships and attacking tankers. But the U.S. Defense Intelligence Agency estimates that Iran also has more than 5,000 sea mines in its arsenal, the New York Times reports. U.S. officials have said that Iran is already starting to lay them. Iran denies this, BTA reports.
There are several types of sea mines. Floating mines float on the surface or just below the surface of the sea. They explode on contact. Anchored mines are tied to an anchor on the seabed. They float at a predetermined depth and detonate on contact. Bottom mines are designed to lie on the seabed, are equipped with sensors, and detonate when they detect a ship or submarine. Sticky mines are magnetic mines that are attached by divers to the hull of vessels and detonate after a predetermined period of time.
The geography of the Strait of Hormuz works in Iran's favor, the American publication writes. The long coastline in the southern part of the strait provides many opportunities for small boats to quickly go out to sea and lay mines. The narrow shipping lanes in the strait leave little room for maneuver. In addition, the water in the narrowest part of the strait is only about 200 feet (about 60 meters) deep, that is, it is shallow enough for mines to be laid.
Since World War I, the military has developed a number of sea mines. The most common were anchored mines. During the Cold War, bottom mines became more common. They contain a much larger amount of explosive than anchored mines and are laid on the seabed. These mines use a combination of sensors to detect when a ship is nearby and detonate with great force.
Iran also has sticky mines. Most of these mines are designed not to sink the ship immediately, but when they explode, the ship is damaged enough to be unable to continue its mission.
Modern tankers, which have inner and outer hulls to prevent oil spills, are unlikely to be sunk by sea mines. Even if the outer hull is punctured by an explosion, the inner hull can remain intact. Additionally, like all modern warships and cargo vessels, tankers are designed with internal watertight compartments that can be sealed to prevent flooding.
While laying minefields can be done quickly, clearing them is a slow and laborious process - and an almost impossible task while fighting is ongoing. To detect mines, mine clearance teams can use a remotely operated vehicle equipped with sonar that scans the water. Once mines are found, they can be destroyed by sending explosive devices or by using divers to defuse them.
Junk, sunken vessels, and other debris clog the seabed, often making mine detection difficult and time-consuming.
Mining, which involves imitating ship signals to set off mines, can be faster than searching for them. But the signals don't always work, increasing the likelihood that unexploded mines will remain in the water.
Reopening the Strait of Hormuz does not require removing every mine. Mine-clearing teams can find passages through a minefield wide enough for ships to safely pass through and mark those corridors.
Once trade is restored, mine-clearing teams can expand their surveys to find and destroy any remaining minefields.
U.S. officials say Iran's new mining activity in the Strait of Hormuz is not particularly fast or effective, but the Iranians appear to be hoping they can lay mines faster than the United States can clear the waterway and thus create an additional deterrent to shipping through the strait.
In 1991, after Iraq laid over a thousand naval mines in the Persian Gulf, it took more than a dozen allied ships almost two months to clear the coast of Kuwait, removing an average of just over one mine per day. Since then, technology has improved significantly, allowing for faster underwater surveys with robotic devices.
Earlier this week, targeting Iran's mine-laying capabilities, US Central Command attacked 16 Iranian mine-laying vessels. Video released by Central Command shows US munitions hitting nine ships, many of which were anchored at a pier. While the US military said it had destroyed larger Iranian warships that could have quickly laid mines in the strait, Iran began using smaller boats for the mine-laying operation on Thursday, according to a US official familiar with the intelligence. Removing every mine in the depots and every ship capable of laying mines would mean US forces would have to destroy all of Iran's civilian maritime infrastructure. The US military may instead choose to maintain armed surveillance drones in orbit over the strait, capable of immediately launching missiles or dropping bombs on any ship seen laying mines, the US publication concluded.