The Saudi air war in Yemen: A case for coercive success through battlefield denial

ABSTRACT

The present-day conflict in Yemen is a valuable case study in the coercive use of airpower. The Saudi-led bombing campaign demonstrates the challenges inherent in applying a punishment-based strategy in a civil war, where coercive mechanisms operate differently than in interstate conflict. The audit from Yemen vindicates the effectiveness of a denial-based strategy and offers insights on the relative utility of interdiction and close air support in advancing that strategy. This examination dissects the campaign, assesses its effectiveness, and extracts insights useful both to the analysis of similar conflicts and to the evaluation of U.S. foreign policy alternatives.

KEYWORDS:

• Saudi Arabia
• Yemen
• airpower
• coercion
• civil war
• UAE

Acknowledgments

The author is indebted to Phil Haun and Frank “Scott” Douglas of the U.S. Naval War College, and to Michael Knights of the Washington Institute for Near East Policy, for their invaluable assistance and advice.

Disclaimer

The opinions expressed herein are those of the author and do not represent the official positions of the United States Navy or Department of Defense.

Disclosure statement

No potential conflict of interest was reported by the author.

Notes

¹ ‘The guardian view on Yemen: Remember the forgotten war’, The Guardian (unattributed editorial), 13 Sept. 2015, <https://www.theguardian.com/commentisfree/2015/sep/13/the-guardian-view-on-yemen-remember-the-forgotten-war>; Sarah Leah Whitson, ‘The U.S. is Quietly Helping Saudi Arabia Wage a Devastating Aerial Campaign in Yemen’, Los Angeles Times, 30 Mar. 2016, <http://www.latimes.com/opinion/op-ed/la-oe-0330-whitson-yemen-strikes-20160330-story.html>; ‘America is complicit in the carnage in Yemen’, New York Times (unattributed editorial), 17 Aug. 2016, <http://www.nytimes.com/2016/08/17/opinion/stop-saudi-arms-sales-until-carnage-in-yemen-ends.html?_r=0>; ‘Yemen’s forgotten war’, The Times (unattributed editorial), 22 Sept. 2016, <http://www.thetimes.co.uk/article/yemens-forgotten-war-lmxkc8lbd>.

² A number of earlier cease-fires and so-called humanitarian pauses predate the Kuwait talks but these were rarely honored and none appear to have represented a viable opportunity for de-escalation. See Helen Lackner, ‘Humanitarian pauses in Yemen?’, Open Democracy, 1 Aug. 2015.

³ Saudi Ambassador to the US Adel Al-Jubeir during official press conference on 25 March 2015, <http://www.cnn.com/videos/world/2015/03/25/nr-walsh-yemen-president-leaves-country.cnn/video/playlists/unrest-in-yemen>.

⁴ UN Security Council, ‘Resolution 2216 (2015)’, 14 Apr. 2015, <http://www.securitycouncilreport.org/atf/cf/%7B65BFCF9B-6D27-4E9C-8CD3-CF6E4FF96FF9%7D/s_res_2216.pdf>.

⁵ Mark Mazzetti and Eric Schmitt, ‘Quiet Support for Saudis Entangles U.S. in Yemen’, New York Times, 13 Mar. 2016, <http://www.nytimes.com/2016/03/14/world/middleeast/yemen-saudi-us.html?_r=0>; Michael Knights, as quoted in a French-language interview with news magazine Paris Match on 9 April 2016, <http://www.washingtoninstitute.org/policy-analysis/view/what-did-the-gulf-coalition-war-achieve-in-yemen>.

⁶ Mazzetti and Schmitt, ‘Quiet Support for Saudis Entangles U.S. in Yemen’. See also: Remarks of Yemeni Foreign Minister Riyadh Yassin, interviewed by BBC News, ‘Yemen Crisis: Saudis Lead Fresh Air Strikes on Houthis’, <http://www.bbc.com/news/world-middle-east-32096934>; remarks of Nabeel Khoury of the Atlantic Council during radio interview with Michael Krasny, ‘Conflict Persists in Yemen Following Saudi Ceasefire Announcement’, KQED Radio, 23 Apr. 2015, <http://ww2.kqed.org/forum/2015/04/23/conflict-persists-in-yemen-following-saudi-ceasefire-announcement/>; remarks of Prof. David DesRoches, Senior Military Fellow at the Near East South Asia Center, National Defense University, during online audio interview with Patrick Ryan from the Saudi–US Relations Information Service, <http://susris.com/2015/03/28/focusksa-intervention-in-yemen-a-conversation-with-david-des-roches/>; and remarks by Antoine Grande, ICRC head of Yemen delegation, interview by Colm Quinn, CSIS podcast ‘Failing Yemen’, 4 June 2016.

⁷ Michael Knights, ‘Gulf coalition operations in Yemen (Part 2): The air war (PolicyWatch 2595)’, Washington Institute for Near East Policy, 25 Mar. 2016, < http://www.washingtoninstitute.org/policy-analysis/view/gulf-coalition-operations-in-yemen-part-2-the-air-war>.

⁸ Jon Lake, ‘Conflict in Yemen’, Air Forces Monthly, June 2015, no. 327, 36–40.

⁹ Jeremy Binnie and Sean O’Connor, ‘Indecisive Storm: Assessing the Saudi-led Air Campaign in Yemen’, Jane’s Defence Weekly, 1 July 2015; Jeremy Binnie and Sean O’Connor, ‘Initial Saudi Air Strikes Lacked Intensity,’ Jane’s Defence Weekly, 13 Apr. 2015. Some surviving SA-2 missiles have reportedly been converted to surface-to-surface weapons. At least one battery appears to have been later restored to operation in a counter-air role. See Jeremy Binnie, ‘Yemeni S-75 SAM Reportedly Back in Action’, Jane’s Defence Weekly, 22 Jan. 2016.

¹⁰ Binnie and O’Connor, ‘Indecisive Storm: Assessing the Saudi-led Air Campaign in Yemen’; Knights and Mello, ‘The Saudi-UAE effort in Yemen (Part 2): The air campaign (PolicyWatch 2465)’, Washington Institute for Near East Policy, 11 Aug. 2015, < http://www.washingtoninstitute.org/policy-analysis/view/the-saudi-uae-war-effort-in-yemen-part-2-the-air-campaign>; Knights, ‘Gulf coalition operations in Yemen (Part 2): The air war’.

¹¹ Statement of Ambassador Al-Jubeir during official press conference on operation Renewal of Hope, 22 Apr. 2015, <https://www.youtube.com/watch?v=ZCOqTyRzvtA>; Knights, ‘Gulf coalition operations in Yemen (Part 2): The air war’.

¹² Meda Al Rowas, ‘Saudi Arabia To Enforce Embargo in Yemen and Conduct Airstrikes As Needed, Sustaining Maritime and Aviation Risks’, Jane’s Intelligence Weekly, 22 Apr. 2015.

¹³ Jeremy Binnie, ‘Yemen’s Ansar Allah Unveils its Rocket Power’, Jane’s Defence Weekly, 29 May 2015; Binnie and O’Connor, ‘Indecisive Storm’; Michael Knights and Alexandre Mello, ‘The Escalating Northern Front in Yemen (PolicyWatch 2490)’, Washington Institute for Near East Policy, 24 Sept. 2015, <http://www.washingtoninstitute.org/policy-analysis/view/the-escalating-northern-front-in-yemen>; Alexandre Mello and Michael Knights, ‘Gulf coalition operations in Yemen (Part 1): The ground war (PolicyWatch 2594)’, Washington Institute for Near East Policy, 25 Mar. 2016, <http://www.washingtoninstitute.org/policy-analysis/view/gulf-coalition-operations-in-yemen-part-1-the-ground-war>.

¹⁴ Alexandre Mello and Michael Knights, ‘The Saudi-UAE War Effort in Yemen (Part 1): Operation Golden Arrow in Aden (PolicyWatch 2464)’, Washington Institute for Near East Policy, 10 Aug. 2015, <http://www.washingtoninstitute.org/policy-analysis/view/the-saudi-uae-war-effort-in-yemen-part-1-operation-golden-arrow-in-aden>.

¹⁵ Mello and Knights, ‘Gulf coalition operations in Yemen (Part 1): The ground war’.

¹⁶ Jigmey Bhutia,’ Yemen: Scores of Houthi Rebels and Government Troops Killed in Fresh Fighting near Saudi Border’, International Business Times, 20 Dec. 2015, <http://www.ibtimes.co.uk/yemen-scores-houthi-rebels-government-troops-killed-fresh-fighting-near-saudi-border-1534191>; Unattributed, “Pro-Government Troops Recapture Strategic Yemeni Port Town,” Middle East Eye, 7 Jan. 2016, <http://www.middleeasteye.net/news/pro-government-troops-yemen-recapture-strategic-port-town-143743280>.

¹⁷ Knights and Mello, ‘The escalating Northern front in Yemen”; Mello and Knights, ‘Gulf coalition operations in Yemen (Part 1): The ground war’.

¹⁸ Binnie and O’Connor, ‘Initial Saudi air strikes lacked intensity’; Jeremy Binnie, ‘Arab Coalition Reportedly Hit by Second Tochka Missile Attack in Yemen’, Janes’s Defence Weekly, 16 Dec. 2015; Simon Henderson, ‘Yemen Missile Strike Jeopardizes Peace Talks,’ Washington Institute for Near East Policy (Policy Alert), 14 Dec. 2015, <http://www.washingtoninstitute.org/policy-analysis/view/yemen-missile-strike-jeopardizes-peace-talks>. The missile attack on Safir on 4 September 2015 killed more than 33 Saudi and/or Emirati soldiers; the by-country casualty count from the attack in Taiz on 14 December 2015 is unclear but that strike appears to have been at least as costly. Houthi-aligned forces have enjoyed better success against military targets with the more accurate Tochka (NATO designation SS-21 Scarab) than with the SCUD C-variant systems that escaped the Saudis’ first phase Decisive Storm attacks. The latter, in combination with mortars and a variety of Soviet-era and allegedly indigenously manufactured surface-to-surface rockets, have been employed for strategic effect in cross-border attacks. See Lori Plotkin Borghardt and Michael Knights, ‘Border Fight Could Shift Saudi Arabia’s Yemen War Calculus (PolicyWatch 2736)’, Washington Institute for Near East Policy, 6 Dec. 2016, <http://www.washingtoninstitute.org/policy-analysis/view/border-fight-could-shift-saudi-arabias-yemen-war-calculus>.

¹⁹ Noah Browning, ‘UAE Says its War in Yemen “Practically Over”’, Reuters, 16 June 2016, <http://www.reuters.com/article/us-yemen-security-emirates-idUSKCN0Z20HU>.

²⁰ Unattributed, ‘UAE Minister Denies Comments on Pullout from Yemen War’, Al Jazeera, 18 June 2016, <http://www.aljazeera.com/news/2016/06/uae-yemen-war-160618060045278.html>.

²¹ Unattributed, ‘Saudi Arabia to Scale Back Operations in Yemen After Deadly Strike’, Middle East Eye, 27 Mar. 2016, <http://www.middleeasteye.net/news/saudi-arabia-plans-draw-down-operations-yemen-after-deadly-air-strike-1437795930>.

²² The analysis that follows draws heavily on the airpower-centric examination of coercive strategy alternatives undertaken by Robert Pape in Bombing to Win (Ithaca, NY: Cornell University Press, 1996), 12–54. The author is indebted to an anonymous reviewer for noting that the concepts of punishment and denial were first introduced and developed, however, by Glenn Snyder in Deterrence and Defense: Toward a Theory of National Security (Princeton, NJ: Princeton University Press, 1961), 8–9, 14–16. The argument here employs these coercive archetypes to analyze the conduct and effectiveness of the Saudi campaign. It bears mention that while there is abundant evidence that the air war was coercive in intent, publicly available sources do not contain sufficient insight to coalition planners’ deliberations and decision-making to confidently state that Saudi campaign managers explicitly understood and categorized their actions in terms of the conceptual frameworks of punishment and denial.

²³ Daniel Byman and Matthew Waxman, The Dynamics of Coercion (Cambridge: Cambridge University Press, 2002), 59–65, 72–76.

²⁴ Mohamed Vall, ‘Saudi-led Air Strikes Hit Yemen for Third Straight Day’, Al Jazeera, 28 Mar. 2015; Reuters in Cairo, ‘Saudi airstrikes in Yemen Target House of Ex-President Saleh,’ The Guardian, 10 May 2015, <http://www.theguardian.com/world/2015/may/10/saudi-air-strikes-in-yemen-target-house-of-ex-president-saleh>.

²⁵ There is good reason to believe that Saudi targeteers had access to detailed data regarding the disposition of these assets as a function of Riyadh’s history of close cooperation with Saleh during his 30-plus year presidency, and the coalition had ample opportunity to re-strike if initial attacks were incomplete. Author interview with Michael Knights (Newport: US Naval War College, 29 June 2016).

²⁶ Pizzi, Michael, ‘Saudis Launch Air Campaign to Defend Yemen Government’, Al Jazeera, 25 Mar. 2015, <http://america.aljazeera.com/articles/2015/3/25/houthi-aden.html>; Michael Knights, ‘Assisting the Arab Military Intervention in Yemen (PolicyWatch 2393)’, Washington Institute for Near East Policy, 27 Mar. 2015, <http://www.washingtoninstitute.org/policy-analysis/view/assisting-the-arab-military-intervention-in-yemen>.

²⁷ Author interview with Knights, 29 June 2016. The next notable report of Houthi leadership death by air strike appears to be the killing of the Houthi second-in-command for Hajjah province on 8 June 2016. Ali Oweida, ‘Top Houthi commander killed in Yemen Airstrike’, Anadolu Agency, 8 June 2016, <http://aa.com.tr/en/middle-east/top-houthi-commander-killed-in-yemen-airstrike/586404>.

²⁸ Houthi organizational history and structure suggest the specter of decapitation might be unlikely to yield a significant shift in behavior regardless. See Barak A. Salmoni, Bryce Loidolt, and Madeleine Wells, Regime and Periphery in Northern Yemen: The Houthi Phenomenon (Santa Monica, CA: RAND, 2010), 189–197, 234–241.

²⁹ Byman and Waxman, Dynamics of Coercion, 65–72, 76–78.

³⁰ Knights and Mello, ‘The Saudi-UAE Effort in Yemen (Part 2): The Air Campaign’; Human Rights Watch, ‘Joint Letter to HRC: Create an International Investigating Mechanism for Yemen’, 23 Febr. 2016, <https://www.hrw.org/news/2016/02/23/joint-letter-hrc-create-international-investigating-mechanism-yemen>; Asa Fitch and Mohammed Al-Kibsi, ‘Heavy Toll in Yemen Conflict Draws Scrutiny’, Wall Street Journal, 10 Dec. 2015, <http://www.wsj.com/articles/heavy-toll-in-yemen-conflict-draws-scrutiny-1449743401>.

³¹ Author interview with Knights, 29 June 2016.

³² Knights and Mello, ‘The Saudi-UAE Effort in Yemen (Part 2): The Air Campaign’.

³³ The author is grateful to an anonymous reviewer for this observation. Although beyond the scope of the discussion here, the reason for this divergence may be at least in part explicable by the different political constraints that apply to democratic and non-democratic regimes. For a broader discussion, see Daniel Byman, ‘Death Solves All Problems: The Authoritarian Model of Counterinsurgency’, Journal of Strategic Studies 39/1 (September 2015), 62–93.; International Crisis Group, ‘Yemen: Is Peace Possible?’ Middle East Report No. 167, 9 Feb. 2016.

³⁴ Human Rights Watch, ‘Targeting Saada: Unlawful Coalition Airstrikes on Saada City in Yemen’, 30 June 2015, <https://www.hrw.org/report/2015/06/30/targeting-saada/unlawful-coalition-airstrikes-saada-city-yemen>.

³⁵ UN Security Council, ‘Final report of the Panel of Experts on Yemen established pursuant to Security Council resolution 2140 (2014),’ 22 Jan. 2016, 163–165.

³⁶ International Crisis Group, ‘Yemen: Is Peace Possible?’; Knights and Mello, ‘The Escalating Northern Front in Yemen’.

³⁷ International Crisis Group, Yemen: Is Peace Possible?

³⁸ The manner and the means by which the Houthis responded are eerily similar to Hezbollah’s reaction to Israeli air strikes during the Second Lebanon War, especially the use of cross-border rocket fire, advanced antitank missiles and anti-ship cruise missiles. See Ralph Shield, ‘Israel’s second Lebanon war: A failure of Afghan model Warfare?’, U.S. Naval War College, 10 May 2007, <http://www.dtic.mil/dtic/tr/fulltext/u2/a470727.pdf>. See also: Michael Knights, ‘What would a Saudi-Iran war look like? Don’t look now, it is already here’, Foreign Policy, 11 Jan. 2016, <http://foreignpolicy.com/2016/01/11/what-would-a-saudi-iran-war-look-like-dont-look-now-but-it-is-already-here/>; Nadav Pollack and Michael Knights, ‘Gulf coalition operations in Yemen (Part 2): Maritime and aerial blockade (PolicyWatch 2596)’, Washington Institute for Near East Policy, 25 Mar. 2016, < http://www.washingtoninstitute.org/policy-analysis/view/gulf-coalition-operations-in-yemen-part-3-maritime-and-aerial-blockade>.

³⁹ Binnie and O’Connor, ‘Indecisive storm’; Knights, ‘The air war’; Knights and Mello, ‘The air campaign’.

⁴⁰ Christopher Boucek, ‘War in Saada: From local insurrection to national challenge’, Carnegie Endowment for International Peace (Middle East Paper Number 110), Apr. 2010; Salmoni, Loidolt, and Wells, Regime and Periphery in Northern Yemen, 129–157.

⁴¹ Knights, ‘Assisting the Arab Military Intervention in Yemen’.

⁴² See coalition military press briefings for Day 3, 4, 6, 9, 17, as translated by the Saudi–US Relations Information Service (SUSRIS), <http://susris.com/special-sections/turmoil-in-yemen-2015/>; Sami Aboudi and Mohammed Mukhashaf, ‘Diplomats and U.N. staff flee Yemen as Houthis target Aden’, Reuters, 28 Mar. 2015, <http://www.reuters.com/article/us-yemen-security-idUSKBN0ML0YC20150328>.

⁴³ See SUSRIS- translated coalition military press briefings for Day 4, 6, 7, 8, 11, 12, 14, 15, 17, 21.

⁴⁴ See William Maclean, Noah Browning and Yara Bayoumy, ‘Yemen Counter-Terrorism Mission Shows UAE Military Ambition’, Reuters, 28 June 2016, <http://www.reuters.com/article/us-yemen-security-emirates-idUSKCN0ZE1EA>. Although there are reports that the coalition had some Saudi special operations force presence on the ground prior to this date, it is unclear whether those elements were qualified for or charged with tactical air control functions. The insertion of the Emirati team suggests not. See Agence-France-Presse,‘Saudi special forces “Involved in Yemen Ops”’, Defense News, 4 Apr. 2015, <http://www.defensenews.com/story/defense/2015/04/04/saudi-special-forces-involved-in-yemen-ops/25287847/>; Nic Robertson and Hakim Almasmari, ‘Saudi Special Forces Help Oppose Houthi Rebels in Yemen, Source Says’, CNN, 3 Apr. 2015, <http://www.cnn.com/2015/04/03/middleeast/yemen-saudi-forces/index.html>.

⁴⁵ SUSRIS- translated coalition military press briefings for Day 24, 25, and 26. For comparison, the Unified Protector air campaign, undertaken with similar objectives and challenges, often fell short of 100 strike sorties per day in its early stages. See Christopher S. Chivvis, Toppling Qaddafi: Libya and the Limits of Liberal Intervention (New York, NY: Cambridge University Press, 2014), 115.

⁴⁶ Michael Horton, ‘Houthis Stand Firm Against Airstrikes in Yemen’, Jane’s Intelligence Review, 27/7 (1 Jun. 2015); SUSRIS- translated coalition military press briefings for Day 19, Day 20, Day 21.

⁴⁷ Mohammad Mukhashaf, ‘Yemeni fighters repel Houthis in Aden After arms drop’, Reuters, 3 Apr. 2015, <http://www.reuters.com/article/us-yemen-security-aden-houthis-idUSKBN0MU0KU20150403>.

⁴⁸ Defected units include the 315th Armored Brigade, the 11th Brigade, and the 11th Border Guards Brigade on 14 April; the 123rd Brigade, 127th Brigade, and 133rd Brigade on 15 April; the 90th Marine Brigade on 16 April; and the commander of the 37th Brigade on 20 April. See SUSRIS-translated coalition military press briefings for Day 20, 21, 22, and 26.

⁴⁹ Mohammed Mukhashaf, ‘Yemen’s Houthi leader accuses Saudi Arabia of seeking to invade’, Reuters, 20 Apr. 2015, <http://www.reuters.com/article/us-yemen-security-saudi-idUSKBN0NA0JB20150420>; Noah Browning and Michael Georgy, ‘Mideast’s Arch-Survivor Stands in Way of Saudi Success in Yemen,’ Reuters, 15 Apr. 2015, <http://www.reuters.com/article/us-yemen-security-saleh-idUSKBN0N61Z120150415>. In ‘Indecisive Storm’, Binnie and O’Connell note that none of these eight brigades were among those that Saudi authorities had previously identified as singled out for attack. Also, the timing of these major defections, all of which occurred in the immediate wake of the passing of UNSCR 2216, suggests that the resolution played a significant role. Nonetheless, it is difficult to imagine the re-alignment would have occurred absent air strikes.

⁵⁰ SUSRIS – translated coalition military press briefing for Day 21 (April 15).

⁵¹ Agence France-Presse, ‘Saudi special forces “Involved in Yemen Ops”’, Defense News, 4 Apr. 2015, http://www.defensenews.com/story/defense/2015/04/04/saudi-special-forces-involved-in-yemen-ops/25287847/

⁵² Agence France-Presse, ‘Situation in Yemen unchanged weeks into air war’, Defense News, 4 May 2015, <http://www.defensenews.com/story/defense/international/mideast-africa/2015/05/04/reality-ground-yemen-unchanged-weeks-air-war/26897097/>.

⁵³ Unattributed, ‘Gulf of Aden Security Review – 22 April 2015‘, Critical Threats Group, <http://www.criticalthreats.org/gulf-aden-security-review/gulf-aden-security-review-april-22-2015?mini=calendar-view/2015-04>; Mohammed Ghobari, ‘Houthis take control of army brigade in Yemen’s Taiz’, Reuters, 22 Apr. 2015, <http://www.reuters.com/article/us-yemen-security-taiz-idUSKBN0ND0QO20150422>.

⁵⁴ Binnie and O’Connor, ‘Indecisive storm’; Mohammed Najib, ‘JTIC Brief: Heavy Fighting Persists in Yemen Despite Weeks of Concerted Saudi-led Airstrikes’, IHS Jane’s Terrorism and Insurgency Monitor, 1 May 2015.

⁵⁵ UN Security Council, ‘Final report of the Panel of Experts on Yemen established pursuant to Security Council resolution 2140 (2014)’, 22–24; Jeremy Binnie, ‘Suspected Iranian missile shipment seized in Arabian Sea’, Jane’s Defence Weekly, 1 Oct. 2015; Jeremy Binnie, ‘U.S. navy seizes another Iranian weapons shipment in Arabian Sea’, Jane’s Defence Weekly, 5 Apr. 2016; Jeremy Binnie, ‘Third Arabian sea arms shipment seized in six months’, Jane’s Defence Weekly, 30 Mar. 2016; Reuters, ‘Yemen: U.S. seizes weapons at sea’, New York Times, 4 Apr. 2016, < http://www.nytimes.com/2016/04/05/world/middleeast/yemen-us-seizes-weapons-at-sea.html?_r=0>.

⁵⁶ Pollack and Knights, ‘Gulf coalition operations in Yemen (Part 2): Maritime and aerial’.

⁵⁷ Fathi bin-Lazrq and Kareem Fahim, ‘Yemen’s despair on full display in “Ruined” City’, New York Times, 10 Apr. 2015, <http://www.nytimes.com/2015/04/11/world/middleeast/aden-yemen.html?action=click&contentCollection=Middle%20East&region=Footer&module=WhatsNext&version=WhatsNext&contentID=WhatsNext&moduleDetail=undefined&pgtype=Multimedia>; Priyanka Boghani, ‘After a month of airstrikes, where does Yemen stand?’, PBS Frontline, 22 Apr. 2015, <http://www.pbs.org/wgbh/frontline/article/after-a-month-of-airstrikes-where-does-yemen-stand/>; Sarah Almukhtar, Jeremy Ashkenas, Joe Burgess, K.K. Rebecca Lai, Sergio Peçanha and Jeremy White, ‘Mapping chaos in Yemen: Houthi fighters continue steady advance’, New York Times, 17 June 2015, <http://www.nytimes.com/interactive/2015/03/26/world/middleeast/geography-of-chaos-in-yemen-maps.html?_r=0>.

⁵⁸ See especially Knights interview with Paris Match, 9 April 2016. Also: Binnie and O’Connor, ‘Indecisive storm’; Knights, ‘The air war’; and Knights and Mello, ‘The Saudi-UAE effort in Yemen (Part 2): The air campaign’.

⁵⁹ Mazzetti and Schmitt, ‘Quiet support for Saudis entangles U.S. in Yemen’.

⁶⁰ Knights and Mello, ‘The Saudi-UAE effort in Yemen (Part 1): Operation golden arrow in Aden’.

⁶¹ Jeremy Binnie, ‘Apaches deployed to Yemen’, Jane’s Defence Weekly, 12 Aug. 2015; Jeremy Binnie, ‘Analysis: Saudi-led coalition opens new front in Yemen’, IHS Defence Weekly, 3 Sept. 2015; Jeremy Binnie, ‘Yemeni pilots carry out airstrikes with AT-802 turboprops’, Jane’s Defence Weekly, 28 Oct. 2015.

⁶² Knights and Mello, ‘The escalating Northern front in Yemen’.

⁶³ See Mazzetti and Schmitt, ‘Quiet Support for Saudis Entangles U.S. in Yemen’ regarding the alleged impact of altitude restrictions and McDowall, Stewart, and Rohde, ‘Yemen’s guerrilla war tests military ambitions of big-spending Saudis’ for a discussion of air-ground integration issues.

⁶⁴ Jeremy Binnie, ‘UAE Set to Get 4,000 more hellfire missiles’, IHS Jane’s 360, 18 May 2016, <http://www.janes.com/article/60428/uae-set-to-get-4-000-more-hellfire-missiles>.

⁶⁵ Binnie, ‘Yemeni pilots carry out airstrikes with AT-802 turboprops’.

⁶⁶ Mello and Knights, ‘Gulf coalition operations in Yemen (Part 1): The ground war’.

⁶⁷ Per Salmoni, Loidolt, and Wells, Regime and Periphery, 143–157. A key difference being the Houthis’ increased lethality with the recent acquisition of advanced antitank missiles.

⁶⁸ Knights and Mello, ‘The Escalating Northern Front in Yemen’. See also the official news release regarding the sale of replacement M1A2S Abrams main battle tanks and armor recovery vehicles to Saudi Arabia. This announcement lists 20 of the requested M1A2S as battle damage replacements but does not specify if or how these losses are split between skirmishing along the northern border and deeper offensive operations within Yemen. Defense Security Cooperation Agency web portal major arms sales news release dated 9 August 2016, <http://www.dsca.mil/major-arms-sales/kingdom-saudi-arabia-m1a2s-saudi-abrams-main-battle-tanks-and-m88ala2-heavy>.

⁶⁹ Although details on other local engagement conditions (to include opposing force ratios) are few, the difference in defensive holdout endurance between Aden and Taiz is potentially instructive to an evaluation of the impact of ground-based terminal attack control on airpower effectiveness. Resistance forces at Aden, where Emirati forward air controllers were present, held out against a determined Houthi assault for 93 days after the controllers’ arrival. In contrast, the Hadi-aligned 35th Armored Brigade, which received air support but had no ground-based terminal attack control services, was overrun at Taiz inside of a month.

⁷⁰ Gamal Hasim, ‘The battle for Taiz’, Al Jazeera, 25 Nov. 2015, <http://www.aljazeera.com/news/2015/11/151124070045342.html>.

⁷¹ Michael Horton, ‘The Houthis’ Counter-Offensive in Yemen: Strategy, Aims, and Outcomes’, The Jamestown Foundation Terrorism Monitor, 13/22 (13 November 2015), <https://jamestown.org/program/the-houthis-counter-offensive-in-yemen-strategy-aims-and-outcomes/>. This counter-offensive should not be read as undercutting the argument for a denial campaign’s success. Horton judges Houthi objectives not as an attempt to retake all of south Yemen, which they likely now realize they cannot hold in light of the new correlation of forces, but as an effort to secure a better outset bargaining position in anticipation of UN-led peace talks in Geneva.

⁷² Per Salmoni et al., the Houthi military effectiveness does not depend overmuch on substantial external support. See Regime and Periphery, 197–204.

⁷³ Phil Haun and Colin Jackson, ‘Breaker of Armies: Air Power in the Easter Offensive and the Myth of Linebacker I and II in the Vietnam War’, International Security 40/3 (Winter 2015/16), 139–178.

⁷⁴ Bruce R. Pirnie, Alan J. Vick, Adam R. Grissom, Karl P. Mueller, David T. Orletsky, Beyond Close Air Support: Forging a New Air-Ground Partnership (Santa Monica, CA: RAND, 2005), 38–60.

⁷⁵ For an overview of Saudi Arabia’s military modernization over the preceding decade, see Daniel R. DePetris, ‘Saudi Arabia’s 5 Most Lethal Weapons of War’, The National, 19 August 2015, <http://nationalinterest.org/feature/saudi-arabias-5-most-lethal-weapons-war-13624>, and Angus McDowall, Phil Stewart, and David Rohde, ‘Yemen’s guerrilla war tests military ambitions of big-spending Saudis’, Reuters, 20 April 2016, <http://www.reuters.com/investigates/special-report/saudi-military/>.

⁷⁶ Lake, ‘Conflict in Yemen’; Peter Felstead, ‘Briefing: Gulf Air Rising’, Jane’s Defense Weekly, 30 October 2013.

⁷⁷ Andrew Tilghman, ‘U.S. Launches Aerial Refueling Mission in Yemen’, Military Times, 8 April 2015, <http://www.militarytimes.com/story/military/pentagon/2015/04/08/refueling-mission/25461213>; Oriana Pawlyk, ‘Remember the War in Yemen? The U.S. Air Force is There,’ Air Force Times, 25 February 2016, <http://www.airforcetimes.com/story/military/2016/02/25/remember-war-yemen-us-air-force-still-there/80935524/>; Brian Everstine, ‘Saudis to Foot the Bill for Refueling in Yemen Fight’, Air Force Times, 7 April 2015, <https://www.airforcetimes.com/story/military/2015/04/07/saudi-pay-air-force-tanker-costs/25408739/>.

⁷⁸ Maggie Michael and Jon Gambrell (The Associated Press), ‘Saudi Coalition Used U.S. Bombs in Obliterating Yemen Market’, Air Force Times, 8 April 2016, <http://www.airforcetimes.com/story/military/2016/04/07/saudi-coalition-used-us-bombs-obliterating-yemen-market/82769640/>; Phil Stewart, ‘U.S. Withdraws Staff from Saudi Arabia Dedicated to Yemen Planning’, Reuters, 19 August 2016, <http://www.reuters.com/article/us-yemen-security-usa-saudiarabia-idUSKCN10U1TL>; McDowall, Stewart, and Rohde, ‘Yemen’s guerrilla war tests military ambitions of big-spending Saudis’. American airborne imagery support augments what the RSAF receives via their own assets operating in Yemen, which include the Chinese-manufacture Predator-equivalent CH-4. See Jeremy Binnie, ‘UAE, Saudi Arabia Operating Chinese UAVs Over Yemen’, IHS Defence Weekly, 18 Dec. 2015.

⁷⁹ Agence France-Presse, ‘Saudi Arabian pilot discusses operation in Yemen’, The National, 4 Dec. 2015, <http://www.thenational.ae/world/middle-east/saudi-arabian-pilot-discusses-operation-in-yemen>.

⁸⁰ Andrew Chuter, ‘RAF bombs diverted to Saudis for Yemen strikes’, Defense News, 16 July 2015, <http://www.defensenews.com/story/breaking-news/2015/07/16/britain-diverts-bombs-destined–raf–help-saudi-fight–yemen/30236031/>; Aaron Mehta, ‘US clears sale of air-to-ground weapons to Saudi Arabia’, Defense News, 16 Nov. 2015, <http://www.defensenews.com/story/defense/air-space/strike/2015/11/16/us-clears-huge-sale-air–ground-weapons-saudi/75868166/>; Chris Pocock, ‘Saudis request huge resupply of U.S. Air-to-ground weapons’, AIN Online, 20 Nov. 2015, <http://www.ainonline.com/aviation-news/defense/2015-11-20/saudis-request-huge-resupply-us-air-ground-weapons>. The UAE has also requested to procure replenishment stocks of PGMs at least a portion of which were expended in Yemen. See relevant major arms sales news releases posted to the Defense Security Cooperation Agency web portal dated 29 May and 5 November 2015, <http://www.dsca.mil/major-arms-sales/united-arab-emirates-uae-guided-bomb-units-gbu-31s-and-gbu-12s> and <http://www.dsca.mil/major-arms-sales/united-arab-emirates-uae-joint-direct-attack-munitions-jdam-sustainment-and-support>, respectively).

⁸¹ See, for example, Human Rights Watch, ‘Bombing businesses: Saudi coalition airstrikes on Yemen’s civilian economic structures’, 10 July 2016, <https://www.hrw.org/report/2016/07/10/bombing-businesses/saudi-coalition-airstrikes-yemens-civilian-economic-structures>.

⁸² Noah Browning and Tom Brown, ‘Air Strike on MSF Hospital in Yemen kills at least 11‘, Reuters, 16 Aug. 2016, <http://www.reuters.com/article/us-yemen-security-idUSKCN10Q1E0>; Alex Emmons, ‘Doctors without borders hospital bombing in Yemen earns rare Saudi Rebuke at state department’, The Intercept, 15 Aug. 2016, <https://theintercept.com/2016/08/15/doctors-without-borders-hospital-bombing-in-yemen-earns-rare-saudi-rebuke-at-state-department/>.

⁸³ Noah Browning and Mostafa Hashem, ‘Saudi investigation largely defends deadly air strikes in Yemen,’ Reuters, 4 Aug. 2016, < http://www.reuters.com/article/us-yemen-security-saudi-airstrikes-idUSKCN10F23J>.

⁸⁴ For an official explanation of dynamic targeting – a USAF operational concept defined by real-time target assignment and best exemplified by the early phase of the Operation Enduring Freedom air campaign over Afghanistan – see the Curtis E. LeMay Center for Doctrine Development and Education <https://doctrine.af.mil/download.jsp?filename=3-60-D16-Target-Dynamic.pdf>. The author is indebted to an anonymous reviewer for this useful reference.

⁸⁵ The RSAF’s performance would seem to confirm rumored complaints about poor training retention and contractor dependence. See Yiftah Shapir, ‘Saudi Arabia goes to war’, National Interest, 29 Feb. 2016, <http://nationalinterest.org/blog/the-buzz/saudi-arabia-goes-war-15349>.

⁸⁶ This is particularly surprising not least because some of these targeting difficulties were identified during RSAF’s participation in the 2009–2010 war in Yemen. See David C. Isby, ‘New swords for the Saudis’, Air Forces Monthly Aug. 2016), no. 342, 71.

⁸⁷ For Emirati Air Force tactical proficiency, see Rajiv Chandrasekaran, ‘In the UAE, the United States has a quiet, potent Ally Nicknamed “Little Sparta”’, Washington Post, 9 Nov. 2014, <https://www.washingtonpost.com/world/national-security/in-the-uae-the-united-states-has-a-quiet-potent-ally-nicknamed-little-sparta/2014/11/08/3fc6a50c-643a-11e4-836c-83bc4f26eb67_story.html>, and Michael Knights, ‘The U.A.E. approach to counterinsurgency in Yemen’, War on the Rocks, 23 May 2016, <http://warontherocks.com/2016/05/the-u-a-e-approach-to-counterinsurgency-in-yemen/>. Regarding UAE military capacity constraints, see remarks of Lieutenant General Vincent Stewart, Director of the Defense Intelligence Agency, during testimony before the Senate Armed Services Committee on 9 February 2016, <https://www.c-span.org/video/?404436-1/james-clapper-testimony-global-threats>.

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Ralph Shield

Commander Ralph Shield U.S. Navy, is an active duty intelligence officer and a distinguished graduate of the U.S. Naval War College (NWC). His most recent previous assignment was as senior defense official and defense attaché to the Republic of Albania.