The Houthi movement, which currently controls the highlands of northern Yemen, is one of Iran’s main allies and has received considerable financial aid, weapons and military training since its inception. After the movement took control of Yemen’s capital, Sana’a, in 2015, an Arab coalition led by Saudi Arabia tried to turn back the clock and remove the Houthi movement from power in the north of the country. This attempt was unsuccessful and after seven years of war with heavy civilian casualties, Saudi Arabia signed a ceasefire agreement with the Houthi regime in Sana’a. This ensured both the continued existence of an Iranian proxy, radical Islamist state and its control of one of the most strategic maritime transportation routes in the world – the Bab el-Mandab Strait that, connects the Indian Ocean to the Suez Canal, and from there to the Mediterranean Sea. It is thus no wonder that the Houthis, encouraged by their Iranian patrons, are now using their strategic advantage to disrupt international commercial shipping in order to advance their ideological goals, one of which is the abolition of the existence of the State of Israel.
The war in the Gaza Strip, which erupted in the wake of the October 7 Hamas assault on Israel, quickly led to Houthi intervention on behalf of Hamas. The intervention began in the form of ballistic missile, cruise missile and drone attacks on southern Israel. The first attack occurred on October 19, 2023, barely two weeks after the outbreak of the war, when a barrage of drones and long-range cruise missiles[1] was fired from Yemeni territory towards Israel (probably targeting the southern port city of Eilat). Most of this barrage was intercepted by a U.S. Navy destroyer stationed in the Red Sea. Saudi Arabia’s air defense system may also have intercepted one or more UAVs from the same barrage. A second barrage of drones, and possibly cruise missiles, was fired on October 27, 2023, in the direction of Eilat. Two drones hit the coast of Egypt’s Sinai Peninsula, and one or more drones were intercepted by an Israeli Air Force fighter jet before entering Israeli airspace. Four days later, on October 31, 2023, the Houthi regime declared a state of war with Israel and launched a long-range ballistic missile toward Eilat, which was intercepted by the Arrow missile defense system in its operational debut.
Over the next two months (November and December 2023), the Houthis continued to launch barrages of drones, cruise missiles, and ballistic missiles at Israel. These were intercepted by American ships, Israeli Air Force planes, and the Arrow system. The IDF has published videos of interceptions of cruise missiles[2] by IAF planes. Evidence in support of this can be found in the remains of a Houthi cruise missile located in southern Jordan, about 60 kilometers east of the Israeli border.[3] This missile likely ran out of fuel before reaching its destination. According to media reports, in December 2023, the Egyptian Air Force intercepted a “flying object” over the town of Dahab in southern Sinai[4] – probably a Houthi drone or cruise missile that was aimed at Eilat but deviated from its course. From the end of November 2023 until the time of writing, there have been no further attempts by the Houthi regime to hit Israel’s territory. It is likely that their Iranian patrons have learned lessons from the failure of the first phase of their air offensive and are now taking steps to improve the Houthis’ long-range capabilities. Presumably, if and when they achieve such improvements, they will renew their attacks. [5]
As noted above, the indirect Iranian intervention in Israel’s war against Hamas through Houthi proxies in Yemen is expressed mainly in an effort to impose a naval blockade on Israel and strike Israeli affiliated shipping, either owned or operated by Israeli companies or heading towards any Israeli port. Yemen’s geographical location and the weapons supplied to it by Iran enable it to implement this effort using a variety of weapons. Although the Houthi regime does not control the northern side of the Bab el-Mandeb Strait, it controls a coastal strip of the southern Red Sea from the port of Hodeida to the Saudi border. This strip is nearly 200 km long and from there anti-ship coastal missiles can be launched across the Red Sea. The Houthis have other powerful means to strike ships far beyond the boundaries of the territory under their control. The simplest means is the physical takeover of merchant ships with the help of troops from helicopters or fast boats. More sophisticated technological means are “suicide” UAVs and anti-ship ballistic missiles (ASBMs).
The ability to hit moving ships with drones was first demonstrated in July 2021, when an Iranian drone hit the Israeli-owned MV Mercer Street tanker. The strike occurred while the ship was sailing off the coast of Oman en route to the Persian Gulf, about 500 kilometers from the nearest Iranian coast. The impact did not sink the ship but caused the deaths of the British captain and a Romanian security guard. This proved the Iranians’ ability to gather reliable information about the identity of merchant ships at sea, pinpoint their locations, and launch long-range drones that can target and damage them. Around the same time, there were several other incidents of drone attacks on merchant ships with ties to Israel, both in the Persian Gulf and in the northern Indian Ocean. These capabilities, together with appropriate training and Iranian intelligence guidance, were transferred to the Houthi regime and are being employed by it in its ongoing blockade campaign.
Even more innovative means currently in the Houthis’ hands are anti-ship ballistic missiles. The “classic” ballistic missile, invented in Nazi Germany and used by it against London and other European cities, was designed to hit stationary targets only, as were the ballistic missiles later developed in the Soviet Union, the United States, China and other countries. The guidance of “classic” ballistic missiles is carried out only in their powered phase, that is, only when the rocket engines are running. Once the rocket motors are shut off, the missile follows a free ballistic trajectory until it hits the selected target on the ground. Non-stationary targets, such as ships, change their position during the free ballistic trajectory and therefore cannot be hit by this kind of “classic” ballistic missile.
The first country to embark on developing ballistic missiles capable of hitting ships on the move was China. For this purpose, the reentry vehicle of the ballistic missile (commonly referred to as its warhead) was provided with navigation and self-steering capability that enables changing and correcting the missile’s trajectory before hitting the target. An optical or radar seeker was installed at the front end of the warhead. The missile is launched in the general direction of the ship, and when the seeker “sees” the target, it locks onto it and sends continuous correction commands to the guidance system – that is, the missile “chases” the target until it collides with it. The Chinese developed this capability to threaten U.S. Navy ships in East Asia, and the Iranians followed them to threaten U.S. Navy ships in the Persian Gulf and beyond. The Iranians’ starting point was the Fateh-110 precision rocket with a range of about 300 km, which has the ability to navigate and steer all the way to the target. The original rocket was designed to hit stationary targets only. In order to enable it to hit moving targets, this rocket was fitted with an optical seeker, and it was dubbed “Khalij Fars” (Persian Gulf). The Khalij Fars was first tested in 2008 and publicly unveiled by Iran in 2011. Since then, longer-range versions of this missile have been developed, some of which were delivered to the Houthis. From photos of the Houthi army’s military parade in Sana’a on September 22, 2023, and according to an analysis by armaments experts[6], the Houthis currently have at least five types of anti-ship ballistic missiles: two with a range of about 500 km and three types with a shorter range, probably between 100 and 200 km. The Houthis are currently making extensive use of these missiles to attack merchant ships and warships in the southern Red Sea and the Gulf of Aden.
On October 19, 2023, the Houthi regime announced the closure of the Bab el-Mandab Strait to Israeli-owned or Israeli-operated ships.[7] Their first step in this campaign was taken on the same day when a squad of commandos arriving by helicopter landed aboard the Galaxy Leader car ferry en route from Turkey to India. The squad took control of the ship and directed it to the port of Hodeida, where it remains to this day. This ship is the property of a Japanese company, one of whose junior shareholders is an Israeli businessman. The crew (which did not include Israelis) was not injured but is prevented from leaving Yemen. Another Houthi attempt to hijack a merchant ship occurred more than a month later, on December 30, 2023. On that date, four armed Houthi boats attempted to seize the container ship Maersk Hangzhou while it was sailing in the Gulf of Aden, outside the Red Sea. Following distress calls from the ship, American planes and helicopters rushed to the ship’s aid. The Americans sank three of the armed boats and killed 10 Houthi crew members on board. The Maersk Hangzhou, which was not damaged, continued on its way into the Red Sea and from there to the Suez Canal. It should be noted that the ship was not en route to an Israeli port and had no connection to Israel. There are reports of two other failed attempts to hijack ships, but these could have been made by Somali commercial pirates. Whether the Somalis acted in conjunction with the Houthi blockade remains unknown.
It seems that after the case of the Maersk Hangzhou, the Houthis abandoned their attempts to hijack ships and intensified their attempts to cause damage with drones, anti-ship cruise missiles, and UAVs, attempts that have continued with some success at the time of writing. Many of the ships attacked had no connection to Israel. It should be noted that these attacks did not completely stop navigation in the area and that commercial shipping traffic through the Red Sea continues despite the Houthi attacks. However, it is unclear whether any Israeli-affiliated ship managed to evade the Houthi blockade and sail this route unharmed. It is reasonable to assume that the Houthis have fairly good information about Israel’s connection to global commercial shipping, but they apparently also rely on fake information in choosing which ships to attack and which not. A review of all Houthi attacks on commercial vessels from the beginning of their naval campaign on October 19 to January 16, 2024 reveals that during these two months, 21 merchant ships were attacked, only seven of which had any affiliation to Israel. Of the ships attacked, one was hijacked and 10 were hit – that is, the success rate of Houthi drones, cruise missiles and ASBMs up to that time was about 50%.[8] It should be noted that despite the physical damage to the ships, none of them were sunk and no casualties were recorded among their crews – a remarkable fact that was also emphasized by the Houthis themselves. It is unclear whether the lack of casualties among the crews stems from a deliberate policy, or whether it is a result of pure chance. The crews on these ships reside and work in limited zones within the total volume of the ships, so statistically the chances of hitting the area where the crews are located are not high. On the other hand, the fact that no ship was sunk is probably due to the Houthi policy of not using their larger naval missiles and drones that carry heavy warheads with hundreds of kilograms of explosives. [9]
The Houthis have not limited themselves to disrupting commercial sea traffic and have also attacked warships of the US, British and French fleets in the Red Sea. The first military ship attacked was the American destroyer USS Carney, which had previously participated in the downing of drones and cruise missiles en route to Israel. The attack, on December 3, 2023, involved at least three drones. The drones were shot down without any damage to the American ship. Six days later, the French destroyer Languedoc was attacked by two drones, which were also shot down without damage to the ship. On December 19, 2023, the US Secretary of Defense announced Operation Prosperity Guardian to ensure freedom of navigation in the Gulf of Aden, Bab el-Mandab Strait and the Red Sea. Another 12 countries have officially joined this initiative, but in practice, it seems that only Britain is actively cooperating in operational activities. The operation has garnered limited achievements in protecting merchant ships, which continued to be attacked even after the launch of the military operation. On January 10, 2024, the Houthis carried out a significant attack on an allied flotilla that included two American destroyers and one British destroyer. The wave of Houthi attacks apparently included 18 drones, two anti-ship cruise missiles and one UAV. According to reports, all the Houthi weapons were intercepted and destroyed by Allied ship defenses, with one cruise missile intercepted by a U.S. Navy fighter jet taking off from the aircraft carrier Eisenhower. Two days later, on January 12, 2024, the US and British navies responded with a large-scale reprisal that included attacks on Houthi military infrastructure and missile sites on Yemeni soil. This and subsequent attacks failed to paralyze the Houthis’ ability to attack merchant ships and warships within the full range of their weapons, from the Gulf of Aden to the southern Red Sea. The exchange of blows between the Houthis and the coalition fleets of Operation Prosperity Guardian continues at the time of writing. Following the coalition ships’ attacks on them, the Houthis expanded their objectives to include merchant ships affiliated with the US and the UK.
Closing straits to hostile ships and navies is not a new phenomenon. This strategy has been employed in past wars. The innovation this time is in weapon systems: the torpedo missiles and long-range coastal guns of past wars have been replaced by anti-ship cruise missiles, drones and ASBMs. Anti-ship cruise missiles are nothing new: the Soviet Styx and the Israeli Gabriel, the French Exocet and the American Harpoon were developed in the 1950s and 1960s. In contrast, the use of drones and ballistic missiles to attack ships is an innovation of Iran’s arms industry. From the information in the sources used to prepare this study, it is possible to estimate the effectiveness of these weapons as of mid-January of this year. The table below lists the numbers of all Houthi weapons systems launched against merchant and military ships, and the number of hits achieved (all hits are on commercial shipping – no warships have been hit so far).
Table 1: Houthi anti-ship weapon scores, October 19, 2023 to January 16, 2024
| ASBMs | UAVs | Anti ship cruise missiles | |
| 16 | 45 | 5 | Fired |
| 6 | 1 | 1 | Hit |
| 38% | 9% | 20% | Rate of success |
The table indicates that the Houthis opted for UAVs as their main weapon for maritime attacks, but that ASBMs too featured prominently. The low scores of cruise missiles and UAVs do not necessarily reflect lack of accuracy and reliability but rather the success of warships from the coalition fleets in shooting down all such weapons aimed at them. On the other hand, most of the ASBMs were aimed at commercial shipping. As for the few ASBMs fired at warships, it is not known if they were intercepted. According to more recent media reports (26.1.2024), a US destroyer succeeded for the first time in intercepting an ASBM fired from Yemen. From this, we can deduce that the ASBMs fired at warships up to that date missed their targets and were not intercepted. Therefore, it is reasonable to assume that the success rate of the ASBMs as shown in the table reflects the technical effectiveness of this weapon system. This efficiency – less than 40% – is not impressive in itself, but it is sufficient to achieve the effect of maritime terrorism and significantly interfere with freedom of navigation off the Yemeni coast.
The cruise missiles, drones and ASBMs used by the Houthis to disrupt maritime traffic are simple, cheap and easy to conceal. Therefore, it is rather likely that the continued attempt of the coalition fleets to suppress the Houthi attacks will not be completely successful. The Houthi campaign has not halted all maritime traffic through the Bab el-Mandab Strait. Since the beginning of their attacks until this writing, fewer than 30 ships have been attacked out of the thousands of ships that have passed through this waterway in the time since. However, the impact of the Houthi disruption is already affecting maritime traffic to Israel and maritime trade worldwide. The Chinese government owned shipping giant Cotsco announced that it would no longer serve Israeli ports. The port of Eilat is effectively empty, and the port of Ashdod (where cars imported from East Asia via the Suez Canal are unloaded) also predicts a certain decline in the scope of its activity. Egypt and Jordan are also feeling the economic consequences of the Houthi attacks: Egypt’s revenues from transit fees through the Suez Canal decreased by 40 percent in January compared to the same period last year.[10] Many shippers, including the giant company Maersk, have changed their shipping routes from East Asia to Europe and are now sailing around Africa instead of passing through the Red Sea. This extends the sailing time by day and weeks and increases the total cost of maritime shipping by millions of dollars. The result is a delay in the supply chain, a halt in production at factories in Europe,[11] and an increase in the prices of a range of products, including oil and gas.
The Houthi campaign to disrupt traffic in the seas near Yemen employs simple and relatively inexpensive weapons that Iran is eager to provide to its proxies in the Middle East. The possibility that they may use similar weapons to disrupt traffic in the Mediterranean Sea has recently been mooted. [12] It should be taken into account that if the Iron Swords war spreads to the northern arena, Hezbollah and the pro-Iranian militias in Syria and Iraq will copy the Houthi strategy and use similar Iranian weapons systems to disrupt Israeli maritime traffic in the eastern Mediterranean. Israeli policymakers must take this into account in all their decisions regarding the continuation of the war.
[1] The term UAV usually means a propeller driven Uncrewed Air Vehicle. The Iranians and their Houthi proxies operate UAVs powered by small jet engines which are popularly termed “Cruise Missiles.”
[2] https://www.youtube.com/watch?v=4B-9Mj-Pgl8
[3] Live Map
[4] Aharam Online “Egyptian Air Defence Forces Intercept, Down Flying Object Off Dahab Coast: Al Qahera News”, December 16 2923, https://english.ahram.org.eg/NewsContent/1/1237/514124/Egypt/Defence/Egypt-forces-intercept,-down-flying-object-off-Dah.aspx
[5] On February 2, 2024, shortly before the publication of the present article, the Houthis renewed their missile fire and launched another ballistic missile at Eilat, which in turn was successfully intercepted by the Arrow anti-missile system. See “Arrow system intercepted a ground-to-ground missile launched by the Houthis at Eilat” YNET February 2, 2024, https://www.ynet.co.il/news/article/r1bO9t99a
[6] Hintz, F. “Houthi Anti-Ship Missile Systems: Getting Better All the Time: International Institute of Strategic Studies January 2024
[7]El Arabia News 19/10/2023
[8] Scharf, A: “The Full Map: All Ships Attacked by Yemen’s Houthis in the Red Sea”, Haaretz January 15, 2024
[9] One exception occurred on January 26, 2024, when an unnamed weapon – probably a UAV – struck the oil tanker MV Marlin Luanda causing a major fire that threatened the ship’s survival. The crew took to lifeboats. This ship is British-owned and has no affiliation to Israel, but the Houthis claim that she has been transporting jet fuel for the Israeli Air Force. It seems that Iranian intelligence accepts less than reliable information. After burning for 20 hours, the fire was extinguished by the firefighting team of an Indian Navy destroyer.
[10]“Suez Canal Authority: Revenues Drop 40% Since Beginning of the Year” Asharq El Awsat, January 13, 2024
https://english.aawsat.com/business/4786756-suez-canal-authority-revenues-drop-40-beginning-year
[11] Waldersee, V. Ringston, N and Mannes, M “Tesla, Volvo Car Pause Output as Red Sea Shipping Crisis Deepens” Reuters January 13, 2024
[12] Iran Threatens Mediterranean Closure Over Gaza Without Saying How” Reuters December 23, 2023, https://www.reuters.com/world/middle-east/iran-threatens-mediterranean-closure-over-gaza-without-saying-how-2023-12-23/
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Photo: IMAGO / ZUMA Wire / Indian Navy
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