Iran’s Advantage Lies Underwater

Swarms of Iranian small boats, smart mines, mini-submarines and hyper-fast torpedoes provide an advantage that keeps the US fleet hundreds of kilometres away.

US President Donald Trump made a big deal out of the fact that the US managed to knock out the Iranian navy’s larger surface ships on the first day of the war, but Iran’s capabilities above and below the water have not been smashed. American ships stay hundreds of kilometers away, and there are good reasons for that. Iran has been preparing for decades and now, not least thanks to completely new weapons systems and tactics, has an advantage that is difficult for the US to counter.

Trump has boasted that the US Navy would escort merchant ships through the Strait of Hormuz, and then that he would open the waterway by force, but the reality is that American aircraft carriers, among others, are forced to stay so far away from the Iranian coast that they have difficulty reaching it with their fighter jets without aerial refueling.

The Strait of Hormuz, which is the waterway between mainland Iran and the Arabian Peninsula, and which connects the Persian Gulf with the Gulf of Oman, is barely 50 kilometers wide, at its narrowest point only 33 kilometers, and on average only 60 meters deep. On the Iranian side, it is bordered by high mountains with countless straits and bays. The shallow depth makes it easy to mine, and makes it more difficult for deep-sea fleets, such as the American one, to take advantage of strategic advantages they otherwise have out in the oceans. Photo: X

Through asymmetric warfare conducted with a small but effective submarine fleet, thousands of small fast boats equipped with naval combat robots, advanced torpedoes, drones and smart mines, Iran possesses the ability to maintain strategic control over the important waterway for months or even years.

A Strategic Nightmare

The Strait of Hormuz is one of the world’s most important lifelines when it comes to international trade, not least because – under normal conditions – around 21 million barrels of crude oil from the oil-rich Gulf states are shipped through the waterway every day, which is a fifth of global consumption, but also a quarter of the world’s natural gas and a third of the world’s raw materials for the production of artificial fertilizers. The war and the measures that Iran is threatening to take against hostile nations are putting pressure on the world economy that can be compared to the 1973 oil crisis. This is not only due to sharply rising fuel and energy costs, but because it could trigger famine on an almost global scale.

At the same time, it is clear that Iran allows around a hundred ships out of the otherwise several thousand to pass through the strait every day – but only for nations that do not support the war against Iran. On March 24, the Bloomberg news agency reported that Iran, “according to informed sources,” has also begun charging selected nations a fee for permission to pass. The fee is the equivalent of $2 million per ship, and is paid in the Chinese currency yuan. An expensive “war tax” may seem like a good deal, but for shipping companies it is still economically advantageous compared to being stuck indefinitely.

The Strait of Hormuz is narrow, 33 kilometers at its narrowest point, and shallow, about 60 meters on average. In addition, Iran has mountainous terrain on its side of the strait and countless small islands and bays along the coast, which gives its military a clear view and the ability to attack targets such as ships from hiding places or mobile positions. At the same time, it does not take much to mine parts of the strait using small boats, submarines, or other more advanced means that Iran possesses.

Robots and Drones in the Air

Iran’s first line of defense against both American warships and merchant ships that it denies passage through the Strait of Hormuz is a large number of anti-ship missiles. They come in a variety of types, ranging from lightweight, hand-held variants that require only a crew of a small group of soldiers, to larger cruise missiles mounted on various types of platforms, such as the domestically produced Noor and Nasr missiles.

Noor anti-ship missile being fired from Tir-2 boat. Still image: Irna

The cruise missiles are around seven meters long, weigh around 700 kilograms and carry an explosive charge of 150 to 165 kilograms. This is enough to seriously damage even medium-sized ships at a long distance. The missiles are further developed variants of Chinese models, the range of which Iran has increased by around 130–170 kilometers, and which can be fired from both land and sea-based systems, such as trucks and small patrol boats. Iran is believed to have a couple of hundred of these missiles, as well as several hundred missiles of smaller variants.

Iran has also, according to information reported by Reuters, ordered the latest export variant of the Chinese CM-302 anti-ship missile, which China developed to combat US aircraft carriers and larger warships. It is unclear whether Iran managed to get some of these delivered before Israel and the US attacked the country, but if so, they would pose a serious threat. With a range of 290 kilometers, high speed and ability to maneuver at low altitudes, they are difficult to combat for US defense systems.

In addition to anti-ship missiles, Iran’s many different types of short-range drones are primarily a threat to civilian ships, which are slow and large targets, which these drones are capable of hitting at sea.

An Armada of Small Boats with Great Impact

Although the Iranian navy’s larger surface ships have been eliminated, a large number of smaller boats, including modified sports boats, still have considerable combat capability, especially around its own coastal waters.

Small boats like the Heidar class, of which there are a couple of hundred according to Iranian data, are very fast attack boats with a speed of up to 110 knots, equivalent to 203 km/h. They can be equipped with various weapons systems such as naval combat robots, torpedoes, drones and even mines.

Iranian small boats equipped with various anti-ship missiles and other weapons systems are intended to attack in swarms, using rapid maneuvers to approach the enemy. Photo: IRGC

According to various international sources, including American statements made during the war, the US and Israel have destroyed “hundreds” of such small boats. However, according to military sources who spoke to CNN, this has not really had a major impact on Iran’s capabilities, as it still has “80 percent of its small boats left.” It is likely that large numbers of the boats are in hidden and protected underground warehouses, ports or bays where they have been camouflaged.

Heidar attack boat, a small boat with very high speed, reported to be as high as 110 knots, can be equipped with various types of naval combat robots, mines and drones. Still image: X

To put it into perspective, various analysts and Iranian spokespeople themselves have stated that before the start of the war, they had around 5,000 small boats in total – all with the potential to attack larger ships, lay mines or send drones towards targets.

Submarines Hunt in the Strait with Super Torpedoes

In addition to small boats that can travel quickly on the surface of the sea, Iran also has submarines, which can be divided into larger submarines and mini-submarines.

The Iris Fateh was a 600-ton submarine and the first of its kind, capable of moving in deep water and firing cruise missiles. It was sunk by the US in an attack on March 3. It also has three Russian-made Kilo-class submarines (around 3,000 tons), two of which are in shipyards for refit and are not in service. The third, however, is still in active service and does not appear to have been sunk. Iran is also building a new, larger type of submarine, the Besat-class, of 4,000 tons, but these are not in service and Israel claims to have bombed the shipyard where they are being built.

Iris Fateh at a performance in 2019. Photo; Tasnim News Agency

Instead, Iran’s mini-submarines are likely to play the biggest role in the coming battles in the area. Iran has about 20 Ghadir-class submarines, which are 29 meters long and weigh around 120 tons. They are built for shallow coastal waters and stick to a maximum depth of 30 meters. This allows them to lie still on the seabed and wait for targets completely silently with little risk of detection from the air by reconnaissance aircraft or drones.

A Ghadir submarine during an exercise. Photo: Irna

The armament is primarily torpedoes, including the advanced Hoot torpedo, which is based on a Russian torpedo technology introduced by Russia in the 1990s with the VA-111 Shkval. The torpedo uses a physical phenomenon called supercavitation, which occurs when the rocket-powered torpedo pushes the water in front of it with great force using its own exhaust gases, causing the torpedo to travel enclosed in a bubble of gas and vapor at very high pressure. This allows for very high speeds, but reduces range.

Hoot is an Iranian supercavitating torpedo that can travel underwater at extremely high speeds, around 370 km/h. Photo: Irna

The Hoot torpedo, according to Iran, can reach around 200 knots, or about 370 km/h, underwater, several times the speed of a standard torpedo. The range is said to be around 10 kilometers, which is a third of what most standard torpedoes can achieve.

Smart Mines – Death Knell for the Region

The last threat is one of the worst, at least in terms of the world economy and the future of the Gulf states. Iran possesses at least 6,000 naval mines.

At present, Iran has not mined the strait to any great extent, but several American media outlets such as CNN claim to have placed around a dozen mines, which is unconfirmed. However, there is no doubt that Iran has the capacity to mine the strait, especially the very narrow areas where tankers can pass, as they need greater water depth. The selective blockade of the strait that we have seen so far could therefore become considerably worse.

Iran has several types of naval mines. Older floating mines include the Mahan 3, a 300-kilogram naval mine that is deployed and then floats erratically with the current or is attached with wires at predetermined depths. Newer versions include the Mahan 7, which has various advanced features.

An Iranian small boat with naval mines of the Maham 3 model during an exercise. Still image: Fars

The Maham 7 is a 220-kilogram (450-pound) bottom mine that can be deployed by small boats or submarines, including the Iranian mini-submarines. It then lies on the bottom, where it uses sensors to detect sound and magnetism that indicate a larger ship is passing overhead, and detonates the explosive charge. This sends a directed shock wave up towards the ship above, causing extensive damage to the hull.

Maham-7, an Iranian-made naval mine that is placed on the bottom and attacks targets above. Photo: Maritime executive

Iran also has access to an unknown number of Chinese EM-52 naval mines, which are the export variant of the domestic naval mine designated Te-1. It is a bottom mine similar to the Maham 7, but looks like a torpedo and is seven meters long. It is more advanced in that it has a rocket-propelled warhead that it launches towards the underside of a passing ship. It also has the ability to be programmed to ignore certain targets and can thus, for example, ignore tankers and other civilian vessels and only attack warships. It is also made of a non-magnetic material, which makes it difficult to find with traditional minesweepers.

An EM-52 naval mine is placed in a torpedo tube on a Chinese submarine during an exercise. Photo: strausscenter

The warhead has a powerful explosive charge of between 150 and 300 kilograms, and when fired it reaches speeds of 50 to 80 meters per second, meaning it only takes one to two seconds from firing to hit its target at the depths at which it can be deployed in the Strait of Hormuz.

Historically Difficult Problem to Solve

Naval mines are a very problematic threat, even for the United States, as has been demonstrated in previous conflicts. During the Iran-Iraq War of 1980-88, Iran deployed approximately 150 naval mines in the Strait of Hormuz during the final year of the war. One of these nearly sank the American battleship USS Samuel B. Roberts.

USS Samuel B Roberts was seriously damaged when it was hit by an Iranian naval mine in 1988. Photo: Naval History and Heritage Command

The Iraqis, for their part, laid 1,157 naval mines off their own coast, over an area about 100 nautical miles wide, south of the Shatt al-Arab River, where the Euphrates and Tigris meet. Although many mines were cleared in the months after the war ended, it took several years to make the waterways safe. As recently as February 1991, the aircraft carrier USS Tripoli and the cruiser USS Princeton struck Iraqi mines and were seriously damaged.

Noor anti-ship missile. Photo: Iranian Ministry of Interior

Iran currently possesses several times that number of mines. An unknown number of these, but likely at least a couple thousand, are considerably more advanced than those used in the late 1980s.

Stopping Iran from mining the waters around and in the Strait of Hormuz is also almost impossible. The only reason Iran does not already choose to mine everything they can, is because it would have paralyzed all trade in the region, including their own. However, there is a risk that the US, forced as it is to comply with Israel’s wishes regardless of the consequences, will ultimately leave no options for Iran, which would then not only strangle the Strait of Hormuz – but cut its throat.