By Kevin Truitte, Columnist
The war in Yemen approaches its fourth year with little major movement towards a peaceful resolution. Since early 2015, the country has been embroiled in a civil war into which regional powers have intervened in support of their own preferred side. The governments of Saudi Arabia and the United Arab Emirates have deployed troops to support the Government of President Abdrabbuh Mansur Hadi, while the Islamic Republic of Iran has supported the Zaidi Shia military-political movement Ansar Allah–also known as the Houthis–and their allies. The war has had strategic implications beyond its borders. Yemen’s western coast falls along the Red Sea, a strategic maritime choke point through which nearly eight percent of global trade passes annually, including major hydrocarbon shipments.[i] From Yemen’s Red Sea coast, the Houthis have conducted increasingly innovative maritime insurgency activities, targeting warships and civilian shipping using anti-ship missiles provided by Iran, remote controlled boats laden with explosives, and other means. The Houthis’ asymmetric maritime insurgent tactics threaten security in the southern Red Sea, allowing the Houthis and their Iranian backers to challenge their adversaries in the strategically vital waterway.
In March 2015, the Houthi movement and allied forces under the former President Ali Abdullah Saleh swept south from the Houthi stronghold in northern Yemen, seizing control over the capital Sanaa and much of the Red Sea coast. The Houthis and their allies drove forces loyal to Yemeni President Hadi all the way to the southern port city of Aden, where only timely intervention by a coalition of Arab countries led by Saudi Arabia and the United Arab Emirates and supported by Egypt, Bahrain, Qatar and others managed to defend the city and reverse Houthi gains.[ii] In the past three and a half years, Coalition forces have slowly clawed back territory from the Houthis and their allies, using special forces and superior weapon systems to press their advantage. Faced with superior forces, the Houthis have been forced to rely increasingly on asymmetrical insurgency tactics to pressure the coalition.
The Houthi’s asymmetric strategy increasingly relies on attacks against maritime targets in the Red Sea from areas of the Yemeni coast they control. The first major weapon the Houthis used effectively against warships in the Red Sea is the Anti-Ship Cruise Missile (ASCM) and other anti-ship missiles and rockets. In 2016, the Houthis first used this type of missile to destroy a civilian vessel used by the Emirati military.[iii] Since then, the Houthis have targeted not only UAE and Saudi warships with missiles, but also American warships.[iv] In October 2016, Houthi missiles targeted the U.S. Navy destroyer USS Mason and the amphibious transport dock ship USS Ponce three times over the course of two weeks, prompting another U.S. Navy warship, the USS Nitze, to retaliate with cruise missiles to destroy Houthi-controlled surface surveillance radar stations on the Yemeni coast.[v] Houthi missiles have also targeted civilian shipping, as indicated by a May 2018 attack that targeted a Turkish cargo ship carrying grain to a Yemeni port.[vi]
The Houthis have also adopted the use of small boats for swarm tactics against civilian shipping in the Red Sea. Carrying light weapons such as small arms and rocket-propelled grenades (RPGs), the Houthis have used these small boat attacks against commercial oil tankers, although they have had only limited effectiveness due to the Coalition’s rapid responsiveness to such incidents.[vii]
One of the more innovative tactics the Houthis employed is the use of remote-controlled, explosive-laden small boats, known as water-borne improvised explosive devices (WBIEDs). The first use of a WBIED by the Houthis occurred in 2017, when one of these remotely controlled boats exploded at the stern of the Saudi Naval Forces frigate Al-Madinah, damaging the warship and killing at least two Saudi sailors.[viii] Similar to their use of manned skiffs, the Houthis have deployed these “drone boats” in groups to target both warships and, as three-WBIED attack on a Saudi Saudi-flagged tanker in January 2018 indicates, against civilian vessels.[ix]
The Houthi maritime insurgent tactics not only damage enemy warships, but more importantly have an economic impact through their threats to attack trade and oil shipments passing through the twelve-mile wide Bab al-Mandeb Strait and further north in the Red Sea. As of 2013, more than three million barrels of oil transited the strait each day.[x] However, the Houthi threats to maritime shipping have been taken seriously by regional oil-producing states. As previously noted, the Houthis have launched attacks against oil and natural gas shipments as well as other types of cargo at the chokepoint. In July 2018, Saudi Arabia responded to the attacks by announcing its temporary suspension of its shipment of oil through the Bab al-Mandeb after two attacks on tankers, while Kuwait also briefly considered also suspending oil shipments through the strait.[xi] In response, the Houthis announced they would unilaterally suspend attacks in the Red Sea against shipping, indicating that the group has strategically used these attacks to coerce the Coalition militarily and economically.[xii]
The maritime insurgency provides additional strategic benefit to the Houthi’s main regional supporter. Iran has long maintained a strong relationship with the Houthis, and since the outbreak of the war has sent weapons and equipment to the movement. Additionally, the Islamic Republic of Iran provides training and technical knowledge in support of the Houthis’ innovative tactics in the Red Sea. Iranian rocket technology has been used by the Houthis and allied forces in Yemen,[xiii] and American and Coalition naval forces have seized small and medium weapons shipments from Iran likely destined to Houthi-controlled ports.[xiv] The WBIEDs employed by the Houthis also bear hallmarks of Iranian assistance in their manufacture and employment: their guidance systems use Iranian-made commercial parts and a Farsi-scripted keyboard, indicating that it was likely designed by Iranian technicians (Anatomy of a Drone Boat, page 4, 10). U.S. Director of National Intelligence Dan Coats further told Congress in mid-2017 that the United States Intelligence Community believed Iran was providing technical knowledge and supporting the production of the explosive drone boats.[xv]
Iran sees the Houthis as a means to leverage pressure on the Red Sea chokepoint as it has done in Strait of Hormuz at the mouth of the Persian Gulf. Statements by top Iranian military figures reinforce this assessment: Head of the Iranian Revolutionary Guard (IRGC)’s Quds Force Major General Qassem Soleimani issued a warning to the United States that “the Red Sea is no longer safe” for America, and another IRGC command appeared to confirm that the Iranians have directed Houthi attacks against shipping in the Red Sea.[xvi]
The Houthis’ insurgency on the Red Sea threatens transit through the waterway. Their tactics represent innovative and increasingly advanced employment of available technology to compete against better armed and technically advanced adversaries. They represent a strategic intent to disrupt safe passage for both warships and civilian vessels in the sea, and provide leverage both for the Houthis in the context of Yemen and for their Iranian supporters in the broader regional context.
[i] Mark Perry, “Chart of the Day: World GDP and Suez Canal Traffic,” American Enterprise Institute, September 5, 2011,http://www.aei.org/publication/chart-of-the-day-world-gdp-and-suez-canal-traffic/.
[ii] “Yemen crisis: Rebels push into central Aden,” BBC, April 8, 2015, https://www.bbc.com/news/world-middle-east-32216854.
[iii]“Emirati crew ‘wounded’ in last week’s Houthi sea attack,” The New Arab, October 5, 2016, https://www.alaraby.co.uk/english/news/2016/10/5/emirati-crew-wounded-in-last-weeks-houthi-sea-attack
[iv]“Saudi Coalition: Yemen Rebels Fired Missile at UAE Ship,” Associated Press, June 14, 2017, https://www.voanews.com/a/saudi-coalition-yemen-rebels-fired-missile-at-uae-ship/3901324.html
[v] Tyler Rogoway, “USS Mason Attacked For A Third Time While US Pushes Saudi Arabia On Ceasefire,” The Drive, October 17, 2016, http://www.thedrive.com/the-war-zone/5591/uss-mason-attacked-for-a-third-time-while-us-pushes-saudi-arabia-on-ceasefire.
[vi] “Houthi rebels launched missile strike against Turkish cargo ship: White House,” Daily Sabah, May 25, 2018, https://www.dailysabah.com/mideast/2018/05/25/houthi-rebels-launched-missile-strike-against-turkish-cargo-ship-white-house
[vii]“Saudi-led strikes ‘destroy’ Houthi boats threatening tanker in Red Sea,” Reuters, May 23, 2018, https://www.france24.com/en/20180523-yemen-saudi-led-strikes-destroy-houthi-boats-threatening-tanker-red-sea?ref=tw ; “Coalition: Houthi-Iranian attack targets Saudi oil tanker west of Hudaydah port,” Al-Arabiya English, April 3, 2018, https://english.alarabiya.net/en/News/gulf/2018/04/03/Coalition-Houthi-Iranian-attack-targets-Saudi-oil-tanker-west-of-Hudaydah-port.html
[viii] “Anatomy if a “Drone Boat”: A water-borne improvised explosive device (WBIED) constructed in Yemen,” Conflict Armament Research, December 2017, available at http://www.conflictarm.com/download-file/?report_id=2550&file_id=2564 ; “Houthi terrorist attack on Saudi warship Al-Madinah,” Arab News, February 6, 2017, http://www.arabnews.com/node/1049986/houthi-suicide-attack-saudi-warship.
[ix] Paul McLeary, “DIY Drone Attacks on Russian, Saudi Targets Signal Change in Fight Against Militant Groups,” USNI News, January 12, 2018, https://news.usni.org/2018/01/12/diy-drone-attacks-russian-saudi-targets-signal-change-fight-militant-groups.
[xi]Keith Johnson, “Iran’s Yemeni Proxies Put Oil Shipments in Crosshairs,” Foreign Policy, July 26, 2018, https://foreignpolicy.com/2018/07/26/irans-yemeni-proxies-put-oil-shipments-in-crosshairs-saudi-bab-el-mandeb-hormuz-houthi/.
[xii]“Yemen’s Houthis halt Red Sea attacks for two weeks,” Reuters, July 31, 2018, https://www.reuters.com/article/us-yemen-security/yemens-houthis-ready-to-halt-red-sea-attacks-official-idUSKBN1KL1W4.
[xiii]Behnam Ben Taleblu and Amir Toumaj, “Analysis: IRGC implicated in arming Yemeni Houthis with rockets,” Long War Journal, August 21, 2016, https://www.longwarjournal.org/archives/2016/08/analysis-irgc-implicated-in-arming-yemeni-houthis-with-missiles.php ; Rick Gladstone, “Iran Violated Yemen Arms Embargo, U.N. Experts Say,” The New York Times, January 12, 2018, https://www.nytimes.com/2018/01/12/world/middleeast/iran-yemen-saudi-arabia-arms-embargo-un.html.
[xiv] “U.S. Navy says it seized weapons from Iran likely bound for Houthis in Yemen,” Reuters, April 4, 2016, https://www.reuters.com/article/us-iran-usa-yemen-arms-idUSKCN0X12DB.
[xv]“Houthi Rebels Carry Out Series of Bomb-Boat Attacks,” The Maritime Executive, August 17, 2017, https://www.maritime-executive.com/article/houthi-rebels-carry-out-series-of-bomb-boat-attacks.
[xvi] Amir Toumaj, “Did IRGC commander say Houthis were ordered to strike tankers?” Long War Journal, August 9, 2018, https://www.longwarjournal.org/archives/2018/08/did-irgc-commander-say-houthis-were-ordered-to-strike-tankers.php.