If Iran blocks the Strait of Hormuz, these are the ballistic missiles it will use

While there currently is a ceasefire between Iran and Israel, and while the US did not strike back after Iran’s missile attack on Al Udeid Air Base, no one expects the region to remain quiet for too long. And one flashpoint seems to be emerging: the Strait of Hormuz, only about 40 km wide at its narrowest point, with about 20 percent of all global oil moving through its waters.

Iran’s parliament has allegedly backed blocking the Strait and there are reports that Iran has started preparations required to mine it. Iran also has a large variety of small boats and one-way attack drones that may be used against shipping, as well as conventional anti-ship cruise missiles.

One of the most dangerous threats, however, are anti-ship ballistic missiles (ASBMs). But what weapons does Iran have, and how could they be countered?

A typical (unguided) ballistic missile has only a 50 percent probability of landing within a few hundreds of meters of its intended target. That accuracy challenge goes up significantly when aiming at ships, which can obviously move. Complicating things further, an ASBM’s range is such that its target will be below the horizon from the launcher and, because much of its flight is ballistic, an ASBM cannot fly a search pattern.

Thus, attacking a ship at sea with an ASBM requires locating and identifying the target prior to launch (for instance from a patrol aircraft) and communicating its approximate position to the missile launch crew, who then must ready the launcher and launch the missile. This takes time, during which the ship’s position changes. During the missile’s flight time, the ship will also move. Based on its last-known position, speed and heading, the ship’s future position can be predicted. However, such a prediction will not be accurate enough to allow the missile to hit the ship.

To close the accuracy gap, Iran has fitted some of its missiles with satellite navigation and aerodynamic control fins, to steer to their intended impact points during the final phase of their flight. A proper ASBM, in addition to control fins, has a seeker that can locate the ship during the missile’s descent.

And over the years, Iran has presented four different types of ASBMs.

The first, called the Khalij Fars (Persian Gulf), was unveiled in 2010 and has a claimed range of 300 km. Its name gives a clear indication of its intended use: It can cover the complete Persian Gulf. The weapon can either use an optical seeker — likely a contrast seeker that uses visible light, meaning it can only be used at daytime — or an infrared seeker that homes in on a heat source such as the ship’s funnel.

The Khalij Fars, with its 300 km range, has a top speed of about five times the speed of sound. This leaves a short response time and means it needs to be intercepted at a significant stand-off distance from its target. As a result of maneuvers it may also come down at a very steep angle.

More recent ASBMs are the Hormuz 1 and 2, which local reports say use either a passive radio-frequency seeker to home in on a ship’s radar emissions or active radar. Their name also seems to be a message, and they have a similar range as the Khalij Fars.

In 2020, the Zulfiqar Basir was introduced (not to be confused with the similarly named Houthi Scud variant) with a claimed range of 700 km. The velocity of a ballistic missile with such a range is too high for it to use an infrared seeker, because of aerodynamic heating of the dome in front of the seeker. This implies it cannot be employed at night, but it can reach far into the Indian Ocean. All these missiles use solid propellant and are launched from inclined launch rails mounted on trucks.

How Might Iran Use Its ASBMs?

What we can expect from an Iranian campaign aimed at closing the Hormuz Strait, using such weapons, becomes clear if we look at the operations by Yemen’s Houthis. Purportedly in support of the Palestinians, since late 2023 the Houthis have attacked ships in the Bab al-Mandab Strait, the Red Sea and Gulf of Aden in a variety of ways, ranging from using small craft carrying armed raiding parties, to unmanned surface vehicles, as well as anti-ship missiles and one-way attack drones. They too have ASBMs, closely related to Iranian missiles. Their Easif, for instance, is a clone of the Khalij Fars, while the Tankil is a clone of Iranian Ra’ad-500 fitted with an optical seeker.

Based on information posted on X by US Central Command, between November 2023 and September of 2024, the Houthis attacked ships with ASBMs more than 100 times and hit at least 12 ships.

The attack on the Marlin Luanda is a clear indication that the ballistic missile indeed was an ASBM. The ship was attacked in the Gulf of Aden, more than 100 km from the Yemeni Coast, south of Aden. However, that part of the coast is not under Ansar Allah control. The closest inland location under their control is at least 200 km from where the ship was hit and a regular ballistic missile is extremely unlikely to hit a ship at sea over such a distance. The Houthi ASBM attacks took place both at night and during daytime, so their missiles use a mix of infrared and visible-light seekers.

The ASBMs did not cause much physical damage. Modern merchant ships are surprisingly resilient to damage, the ASBM warheads are comparatively small, and it seems that in some cases the missiles either had no warhead, or their warheads did not fuse properly. Only one of the ships that was hit, the Rubymar, sank. The Islander was hit by two missiles and the Laax by three, but they stayed afloat. The attacks did result in a few casualties, with three fatalities aboard the True Confidence and multiple of its crew members being injured.

The Houthis do not have cause a lot of physical damage to achieve their goals, though. They claim to support the Palestinians but use their attacks to further their own goals in the conflict in Yemen, increasing or decreasing their intensity depending on events unrelated to Gaza. Their attacks lead to an increase in shipping insurance premiums and, consequently, a roughly 60 percent decrease in the number of large merchant ships traveling through the Red Sea with many ships between Asia and Europe taking the longer route around Africa instead.

Their number as never returned to its old level, despite a lull in attacks in the last few months. And traffic may dip further, following this month’s Houthi attack on the Greek-operated bulk-carrier Eternity C, which sank with multiple of its crew members killed, missing or kidnapped.

How the Houthis manage to find the ships they target over long distances is unclear. Iranian ships may have provided targeting data and Russia allegedly provided satellite data. Ansar Allah explicitly called upon ships in the region to not switch of their transponders, so they may also have been using AIS (Automatic identification systems) to find target vessels. They were also suspected of using land-based radars to find ships. (In 2016, the US launched cruise missiles at three radar sites in Yemen, in response to the Houthis allegedly launching anti-ship missiles at the USS Mason.)

How Can Iran’s Anti-Ship Missiles Be Stopped?

To protect merchant shipping, multiple navies operate in the Red Sea and Gulf of Aden. Their experience shows that defending ships against ASBMs is possible, but costly. An ASBM represents a dangerous threat.

During a seven-month deployment to the region, in early 2024, the US Arleigh Burke class destroyer USS Carney was involved in 51 engagements, including several against ASBMs. According to the ship’s commander, engagements would take between nine to 20 seconds total.  The US Navy expended at least 120 SM-2 missiles and 80 of the faster and more expensive SM-6 missiles during the fight with the Houthis, with the latter most likely used against the ASBM threat.

European ships also played a role. HMS Diamond, a Royal Navy Type-45 destroyer, intercepted a ballistic missile, while the French FREMM frigate Alsace shot down three, using Aster missiles (known as Sea Viper in Royal Navy service). Israeli, British and US air strikes against Houthi missile infrastructure, port facilities and leadership targets did not stop the attacks, even though US President Trump announced a ceasefire in May 2025.

Based on this experience, if Iran were to choose to block the Hormuz Strait, military options to defend ships from ASBMs are limited. A defensive fight will require large numbers of expensive surface-to-air missiles. Since there is limited production capability to replenish stocks, this reduces the numbers available for a potential future peer-conflict.

Even with military protection, merchant ships will be vulnerable, especially in the Strait itself, and unlike the Red Sea, there is no alternative route. Furthermore, ships will be safe nowhere in the Gulf, due to the naturally constrained geography. Longer-range ASBMs, like the Zulfiqar Basir, could even threaten shipping in the Indian Ocean.

While Iran’s Air Force has suffered attrition in Israeli strikes, they have unmanned aerial systems (UAS) that can hunt for ships at sea, as well as a fleet of (fast) patrol boats. These would be obvious targets for any military action aimed at defending shipping, but given how narrow the Strait is, targeting there can even be done from mountain peaks nearby.

Destroying the missiles and the associated infrastructure on the ground or attacking wider-ranging targets may be an alternative. This has not worked against the Houthis, though, and the potential outcome against Iran is unclear.

The reality is, like the Houthis, Iran does not have to do a lot of damage to cause disruption. If Tehran moves forward and truly plans to hold ships at risk in the region, the US and its partners will have few good options — with major economic impacts on a global scale.

Ralph Savelsberg, a member of the Breaking Defense Board of Contributors, is associate professor at the Netherlands Defence Academy in Den Helder, specializing in missile defense. This article does not reflect any official position or policy of the Government of the Netherlands.