Axis Rising: Iran’s Evolving Regional Strategy and Non-State Partnerships in the Middle East
October 11, 2018
Disclaimer: The author is an employee of the U.S. government, currently on leave from his employment. All statements of fact, opinion, or analysis in this work are those of the author and do not reflect an official position or views of the U.S. government.
- Iran’s intervention into the wars in Syria, Iraq, and Yemen transformed the strength and scope of the “axis of resistance,” the decades-long partnership between, Iran, Hezbollah, and the Syrian regime. Tehran has secured military footholds, committed partners, and lasting influence in each theater.
- Tehran’s motivations evolved during each conflict. Iran began with primarily defensive goals of defending allies and preserving the axis, and then transitioned to offensive goals against Israel, the United States, and Saudi Arabia.
- The cauldron of war forged new military strength, political legitimacy, and a regional mindset amongst Iran’s partners. These groups view Tehran and each other as battlefield partners, ideological allies, and separate flanks in a common regional front.
- As Iran’s axes have strengthened and evolved, so, too, have their relationships with Tehran. Affiliated groups operate along a dynamic spectrum with Iran from ally to proxy—determined by the groups’ capabilities, history, and influence with Iran.
- The axis of resistance today operates less like a “patron-proxy” relationship and more as an Iranian-led alliance , centered on collective security and extended deterrence bolstered by expeditionary power
- The evolution of the axis into an alliance calls for a fundamental shift in how the national security community conceptualizes the Iran challenge and its affiliated groups and poses complex challenges for U.S. policymakers and regional allies.
Asai’b Ahl al-Haq Commander Qais al-Khazali in southern Lebanon, overlooking the Israeli villages of Metulla and Kiryat Shemona with Hizballah commanders, December 2017. Source: https://www.memri.org/tv/qais-khazali-at-israel-lebanon-border
Last December, Qais al-Khazali peered out over northern Israel. Enjoying a commanding view from Lebanon, Khazali, leader of Iraqi militia Asa’ib Ahl al-Haq (AAH), pledged to support Hezbollah in a war with Israel. Flanked by Hezbollah commanders, filmed by AAH’s TV network, Al Ahad, and rebroadcast by Hezbollah’s, Al Manar, Khazali proclaimed, “We are here with Hezbollah to declare our total readiness to stand together with the Lebanese people.”
How did we get here—an Iraqi militia pledging to fight and die alongside a Lebanese one against Israel? Khazali’s visit is a starting point to study the evolution of Iran’s regional strategy post-Arab Spring and its means to execute it, the axis of resistance. This paper explores Iran’s goals and motivations in the wars in Syria, Iraq, and Yemen; the growing capabilities, expanding regional roles, and evolving ties of the non-state groups Iran backs; and how the axis now resembles an alliance. The paper posits courses of action for Iran in the coming years and the implications for the United States and regional partners.
The Axis Saved . . . and Emboldened
Portrait banners of Hizballah Secretary General Hassan Nasrallah, Iranian Supreme Leader Ayatollah Ali Khamenei, Syrian President Bashar al-Asad, and Russian President Vladimir Putin hanging in Damascus, Syria, January 2017. Source: IranTalks, Twitter Post, February 8, 2014, 9:59 p.m.,https://twitter.com/IranTalks/status/432393350793019392
An evolving set of motivations drove Iranian intervention in Syria, Iraq, and Yemen. At the outset, Iran had mainly defensive aims, seeing strategic threats to allies, Shia communities, and the broader axis that compelled deeper involvement. As fronts stabilized, Tehran’s ambitions expanded and turned more offensive, leveraging local partner military gains into a stronger regional position against Israel, the United States, and Saudi Arabia.
- Syria : The Assad regime starting in 2013 faced growing pressure from the Syrian opposition, intensifying in 2015 as the Islamic State pushed into western Syria. Seeing the regime—the lynchpin of the axis—at risk of collapse, Iran and Hezbollah surged into Syria. a,1,2,3,4,5 Bolstered by Russia’s intervention in 2015, and culminating in the 2016 capture of Aleppo, the axis turned the tide of the war, preserving Assad in Damascus, Hezbollah in Lebanon, and Iran’s power projection in the Levant. 6,7,8 With its core goals met, Iran in 2017 moved to bolster the axis’s strategic position against the United States and Israel. Pro-regime forces pushed east to the Euphrates River to check U.S. expansion, and south to expand axis capabilities and create a second front against Israel adjoining Lebanon. 9,10,11,12,13,14
- Iraq : As the Islamic State stormed across Iraq in 2014, Iran faced the prospect of a Salafi-jihadist state on its border, the loss of strategic depth, and the mass slaughter of fellow Shia. Perceiving a strategic threat, Iran sent arms and advisors to factions of the Popular Mobilization Forces (PMF), leaning on core militia partners the Badr Organization, Katai’b Hezbollah (KH), and Khazali’s AAH to halt the Islamic State’s march . b,15,16,17,18,19 With the Islamic State in retreat by 2016, Iran and PMF partners expanded their objectives and moved to contain the U.S. footprint in Iraq, paralleling the U.S.-led coalition campaign up the Tigris River, and to expand their control toward the Syrian border, creating a ground corridor from Iran to Syri. 20,21,22,23,24,25
- Yemen : In 2015, a year after Houthi rebels seized Sanaa, the Saudi-led coalition started to roll back Houthi gains, ousting them from Aden and posturing toward their northern Yemeni stronghold. Seeing no direct threat to Iran, but the need to aid a Shia ally and a chance to check Saudi ambitions, Iran stepped up its military support. 2627 By 2016, with the Houthi controlling the capital and the north, Iran moved to further augment Houthi capabilities for the long-term, and pull Riyadh into a deeper quagmire. 28,29 Launching ground raids and missile strikes into Saudi territory and contesting maritime waters, the Houthis have since extended their and Iran’s reach into and around the Arabian Peninsula. 30,31,32,33,34,35,36,37,38,39,40
The Axis Deepens
Iraq militia Harakat Hezbollah al-Nujaba posts Nujaba posts to its official Facebook page photos of IRGC-QF commander Qassem Soleimeni visiting Iraqi and Syrian pro-regime forces after defeating ISIS in the Syria-Iraq border town of Albu Kamal, November 2017. Source: Aymenn J Al-Tamimi, Twitter Post, November 15, 2017, 6:35 a.m., https://twitter.com/ajaltamimi/ status/930806591938494464
The experience of war strengthened Iran’s ties to non-state groups and transformed partner militias into regional actors. This broadening of the axis—to include non-state groups in Iraq and Yemen—and the deepening of ties with these partners—has expanded Iran’s influence and power projection, with three defining features:
- Paramilitary: Iran’s operational approach is paramilitary, deploying the Qods Force (QF)—the special forces arm of the Islamic Revolutionary Guards Corps (IRGC)—to train, advise, and enable local actors.c,41,42 Such an approach provides Iran efficiencies, achieving outsize operational effects for a small, low-cost footprint; flexibility, to scale Iran’s presence up or down depending on need; and sustainability, building partner strength and allegiance to secure Iranian interests over the long term.
- Expeditionary: Iran and affiliated militia have learned how to conduct and sustain foreign campaigns. Hezbollah, for example, maintained advisory missions in Yemen with the Houthis and in Iraq with PMF, as well as a prolonged ground campaign in Syria, where Hezbollah and Iran have led PMF, Syrian, Afghan, and Pakistani Shia militia on regime offensives. 43,44,45,46,47,48,49,50,51,52,53,54,55,56,57,58
- Interoperability: Iran now maintains a diverse pool of combat-tested manpower with experience fighting jointly.59,60 Iran and the axes acquired warfighting skills in a variety of military operations: urban warfare, in Aleppo and Tikrit; mountain and desert clearing operations, on the western and eastern ends of Syria, respectively; and cross-border raiding, from Yemen into Saudi Arabia.61 62,63,64,65
The experience of war strengthened Iran’s ties to non-state groups and transformed partner militias into regional actors
The Axes Strengthen
Along with expanding military reach abroad, Iran’s affiliated non-state groups have also emerged stronger at home. With growing military capacity and political skill, these partners have legitimized their arms, checked domestic rivals, and consolidated support amongst their bases.
- Evolved since the 2006 war with Israel and transformed by the war in Syria, Hezbollah is a full-spectrum military force unrivalled by the Lebanese state—a state in which the group plays a key political role.d,66,67 Hezbollah holds Cabinet ministries, National Assembly seats, and cross-sectarian alliances, most vitally with Christian President Michel Aoun, giving the group political cover for its arms and a de facto veto over state policy.68,69 Providing Shia constituents political voice, social services, and, as espoused by Nasrallah and the media arm Al Manar, an inspiring narrative of Shia strength and identity, Hezbollah is entrenched as leader of Lebanon’s Shia. 70
- Similar to Hezbollah, key Iran-backed PMF militias have emerged from war stronger, legitimized, and poised to capitalize politically. 71,72PMF militia gained military skills, newfound influence in northern and western Iraq, and legitimacy in Baghdad through the war against the Islamic Stat. 73,74 With rising influence, maturing political acumen, media savvy, and a “victory” narrative, PMF’s Fatah alliance performed strongly in May’s parliamentary elections, led by Hadi al-Amiri’s Badr Organization and now Khazali’s AAH, ensuring a key role in the next Iraqi government.75 Like Hezbollah, Iran-backed PMF militias are implementing post-war reconstruction and social welfare programs the Iraqi state cannot, bolstering their popularity. 76,77
- The Houthis have weathered mounting Saudi-led coalition pressure, economic and humanitarian turmoil, and a fracture with erstwhile ally Ali Abdullah Saleh, to retain and strengthen their hold on power. 78,79 Houthi leader Abdul Malik exploits coalition attacks to underscore a narrative of resistance and defense of the Yemeni nation—a message reinforced by the Houthi media outlet, Al Masirah. 80 Expanding military reach, growing diplomatic experience, and grassroots strength ensure the Houthis a powerful seat at the negotiating table if peace talks resume and a central role in Yemen’s future. 81
The Axis Evolves
As axes’ military and political strength evolved, so, too, did their relations with Tehran. Iran’s affiliated groups operate along a partnership spectrum, from ally to proxy. While Iranian direction and support remain critical to all axes, a group’s influence with Iran and autonomy over decisionmaking varies with their strength as an Iranian partner and maturation as a domestic actor.
- Hezbollah is Iran’s closest ideological and military ally. Iran relies on Hezbollah to devise and execute strategy, empowers the group to pursue its own military and political priorities, and trusts it will balance support for Iran with domestic obligations.82,83
- Iran-backed PMF militias exist across the partner-proxy spectrum. Capable militia and political groups such as Badr Organization and AAH have developed into Hezbollah-esque political-military allies.84,85 Military-centric groups like KH and Harakat Hezbollah al-Nujaba (HHN) serve as battlefield partners in Iraq and Syria under IRGC-QF direction.86,87 Some smaller PMF militias serve as true Iranian proxies, carrying out niche missions such as protecting Shia holy sites or augmenting military operations.88
- The Afghan Fatemiyoun, Pakistani Zeinabiyoun, and several Syrian Shia militia serve as Iranian proxies. Iran recruited, trained, equipped, and deployed these militias to Syria, fighting under Iranian or Hezbollah command.89,90,91,92,93,94
- The Houthis are an Iranian ally but more independent in decisionmaking and less integrated into regional operations than Hezbollah.95,96 The relationship is essentially an Iranian “train-advise-assist” mission with a like-minded but independent partner.97
The axis provides Iran reach, power, and influence across the Middle East but, like most alliances, poses challenges and vulnerabilities. Potential weaknesses in the axis could hinder Iran’s strategic ambitions, operational scope, and capacity to sustain the alliance.
- Strategic Divergence: As Iran’s partners become stronger, they could grow independent or even split with Tehran, as occurred with Hamas over the Syrian war and with Shia cleric Muqtada al-Sadr in Iraq.119,120 If Iran’s militia partners are normalized or integrated into states, they may no longer share the same external threat perception and ideological zeal that once bound them to the axis. Iran’s partners may chafe under a heavy Iranian hand, have constituents grow tired of conflict, and see rivals exploit it for political gain—leaving them less willing to deploy abroad or support an Iranian presence at home.
- Domestic Focus: The summer 2018 protests in Iran highlighted the risk of widespread domestic unrest and discontent with the IRGC’s grip on the economy and spending on foreign wars. 121,122 Interventionists, namely IRGC-QF commander Qassem Soleimani, have driven Iran’s regional policy in recent years;123 turmoil at home could shift the balance of power in Tehran towards President Hasan Rouhani and leaders who favor a less militarized foreign policy and greater focus on diplomatic engagement and domestic issues.124
- Financial Shortfalls: The axis requires money to arm Iran’s partners and sustain their military campaigns. 125,126 If Iran’s economy worsens, Tehran could be forced to curtail regional deployments and support to allies. Since Iran’s axis hinges on the credibility of extended deterrence, a weakening in partner capabilities—vis-à-vis adapting and increasingly capable adversaries—could undermine Iranian strategy.
Potential weaknesses in the axis could hinder Iran’s strategic ambitions, operational scope, and capacity to sustain the alliance.
Axis Courses of Action
Continuing regional turmoil, rising tensions with state rivals, and growing confidence from recent victories suggest Iran will continue military adventurism in the coming years. But to what extent, and for what purpose? Iran has several courses of action (COA) to pursue.
- The key drivers shaping Iran’s COA selection will likely be: Tehran’s threat perceptions of adversaries; the capability, will and need of the axes; opportunity for gains against state rivals; and Iranian domestic constraints.
- We assume Tehran seeks to manage escalation with state rivals to avoid major conflict and will maintain a primarily paramilitary, expeditionary, and joint warfare approach.
COA 1: Retrench : Content with military gains abroad and facing economic woes at home, Iran pulls back its regional commitments, as domestic issues occupy Tehran’s attention. With partner strong, battlefields stable, and no strategic threat from regional rivals, Tehran adopts a defensive posture and maintains only small cadres of IRGC-QF to advise allies, leaning on Hezbollah to lead them.
COA 2: Reinforce : Iran sustains or increases regional interventions, driven by growing internal threats to allies, such as a resurgent ISIS in Syria and Iraq, or external threats from regional foes, such as escalating Israeli action in the Levant or a Saudi-UAE ground offensive in Yemen. Still seeking to minimize the Iranian footprint, Tehran augments IRGC-QF advisors with Hezbollah infantry and Shia “foreign legion” fighters. Iran forward deploys more sophisticated weapons to the battlefield, while also transferring them to key allies.
COA 3: Redouble : With regional tensions escalating, military hardliners ascendant in Tehran, Iran’s economy recovering, and Iranian allies strong at home, the axis goes on the offensive. Iran surges manpower and high-end weaponry to the field, while partners sustain or increase foreign deployments. Tehran’s aggressive posture could take several forms, such military offensives to increase gains in current theaters, targeted or lethal action against rivals in or adjoining those theaters, or expanding into new theaters, such as:
- Palestinian Territories : Rapprochement with and reinforcement of Hamas would provide the axis another means for direct pressure on Israel and regaining support on the Arab street as the vanguard of resistance.127,128
- Arabian Gulf: Iran could strengthen Shia militants in Bahrain and Saudi Arabia’s Eastern Province, fomenting uprisings or providing them Houthi-like capabilities to pressure and punish Saudi Arabia and Gulf allies.129,130,131
- Afghanistan : Iran could complement its ties to the Taliban and leverage the Fatemiyoun and Zeinabiyoun to pressure or attack U.S. forces or build a long-term ally to counter U.S.-aligned Afghan political and military factions.132,133
Considerations for the U.S. and Regional Allies
Iran has secured influence and footholds in key Middle East theaters and is emboldened to pursue a more aggressive strategy against regional rivals. An ascendant axis poses a formidable test to U.S. strategy in the Middle East, a direct threat to U.S. regional allies and interests, and key challenges for policymakers:
Rethinking “Proxy Wars”: Analyzing Syria, Iraq, and Yemen as Iranian “proxy wars” is incomplete at best. Iran has multiple motivations—defensive and offensive, strategic and ideological, pragmatic and punitive—driving intervention. Contesting state rivals is an Iranian objective but may not be the primary one. The needs of its partners—not Iran’s—often drive battlefield priorities. Effective strategy requires an accurate diagnosis of the nature of these wars and the motivations of the combatants.
Resilient Axes: Severing Tehran’s support to its partners is necessary but likely insufficient to weaken Iran’s regional influence because of the strength and resiliency of the axes. These non-state groups now have requisite military, political, and constituent strength to weather a slowdown in Iranian support. Countering Iran’s influence requires a broad, regional strategy to contain and weaken the axis and tailored, local strategies to temper and degrade individual partners.
Rollback Requires Force: The axis invested time, blood, and treasure into the region’s wars and now “own the ground.” Rolling back Iranian and partner influence—such as degrading axis military architecture, empowering rivals, or negotiating Iran’s withdrawal—likely requires coercive diplomacy or military force. Strategists must weave a tight thread: too little pressure is insufficient to reduce Iran’s influence or compel withdrawal; too many risks driving Iran and allies even closer together—or escalating into all-out war.
Risk Trade-offs: Weakening or expelling Iran from the region could work at cross-purposes with other U.S. goals. Without viable U.S. and host-nation alternatives, Iran’s departure from or reduction in support to allies in Syria and Iraq could create openings for an Islamic State or al Qaeda resurgence. In Yemen, al Qaeda in the Arabian Peninsula could again exploit a Houthi rollback, as it did in 2015, to expand influence. 134 The complexity of Middle East battlefields necessitates policy prioritization and realistic assessment of risk trade-offs.
Regional Tinderbox: The axis commitment to mutual defense and geographic dispersion of capabilities risks conflict in one theater reverberating in another and escalating into regional war. For example, military action against Hezbollah in Lebanon could trigger PMF allies in Iraq or the Houthis in Yemen to retaliate against Hezbollah’s perceived aggressors. Should conflict escalate, the axis probably is positioned to prosecute simultaneous campaigns on multiple fronts.
The axis invested time, blood, and treasure into the region’s wars and now “own the ground.” Rolling back Iranian and partner influence likely requires coercive diplomacy and/or military force.
Conclusion: Better Know Your Enemy
Transformed through the region’s war, Iran and a growing coterie of non-state groups are now committed and capable members of the axis of resistance. Iran-backed Iraqi PMF, Yemen’s Houthis, and Shia militia across the Middle East and South Asia have joined core axis members Iran, Hezbollah, and the Syrian regime in the belief that they are separate but allied flanks in a united front against shared enemies. It is these bonds, beliefs, and capabilities forged through war that brought Qais al-Khazali to Lebanon, and credence to his pledge to join Hezbollah in a war against Israel.
Brian Katz is a visiting fellow in the International Security Program at the Center for Strategic and International Studies in Washington, D.C.
CSIS Briefs are produced by the Center for Strategic and International Studies (CSIS), a private, tax-exempt institution focusing on international public policy issues. Its research is nonpartisan and nonproprietary. CSIS does not take specific policy positions. Accordingly, all views, positions, and conclusions expressed in this publication should be understood to be solely those of the author(s).
© 2018 by the Center for Strategic and International Studies. All rights reserved.
a For more on Hezbollah’s military intervention in Syria, see: “The Escalating Conflict with Hezbollah in Syria,” CSIS International Security Program, Seth Jones and Maxwell Markusen, June 20, 2018; and "Hizbollah's Syria Conundrum." International Crisis Group Report, March 14, 2017.
bThe PMF, or Hashd al-Shabi, contains three distinct factions, based on various subgroups’ respective allegiances to Ayatollah Ali Khamenei, Ayatollah Ali al-Sistani, and Muqtada al-Sadr. This paper will primarily discuss Iran-backed, Khamenei-allegiant groups. For more on the PMF, see: “The Popular Mobilization Forces and Iraq’s future”, Renad Mansour and Faleh Jabar, Carnegie Endowment for International Peace, 28 April 2017; and "Iraq's Paramilitary Groups: The Challenge of Rebuilding a Functioning State." International Crisis Group, July 30, 2018.
c For more on the history of the Qods Force and its commander, Qassem Soleimani, see: “The Shadow Commander,” Dexter Filkins, The New Yorker. September 30, 2013.
d For more on Hezbollah’s military evolution and capabilities, see “Hezbollah as an Army,” Yiftah Shapir, The Institute for National Security Studies, January 2017; and "Hezbollah's Missiles and Rockets," Shaan Shaikh and Ian Williams, CSIS, July 5, 2018.
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2 Amir Toumaj, “Death of a General: What Shaban Nasiri Reveals About Iran’s Secretive Qods Force,” War on the Rocks, March 23, 2018, https://warontherocks.com/2018/03/death-of-a-general-what-shaban-nasiri-reveals-about-irans-secretive-qods-force/.
3Seth Jones and Maxwell Markusen, “The Escalating Conflict with Hezbollah in Syria,” Center for Strategic and International Studies, June 20, 2018. https://www.csis.org/analysis/escalating-conflict-hezbollah-syria.
4 Marc Lynch, The New Arab Wars: Uprisings and Anarchy in the Middle East , (New York: Public Affairs, 2016), 232.
5Anne Barnard, Ben Hubbard, and Isabel Kershner, “Iran, Deeply Embedded in Syria, Expands ‘Axis of Resistance’,”New York Times, February 19, 2018, https://www.nytimes.com/2018/02/19/world/middleeast/iran-syria-israel.html.
6 Martin Chulov, Saeed Kamali Dehghan, and Patrick Wintour, “Iran hails victory in Aleppo as Shia militias boost Syria's Bashar al-Assad,” The Guardian, December 14, 2016,https://www.theguardian.com/world/2016/dec/14/iran-aleppo-syria-shia-militia.
7 Ben Hubbard, “Iran Out to Remake Mideast With Arab Enforcer: Hezbollah,” New York Times, August 27, 2017,https://www.nytimes.com/2017/08/27/world/middleeast/hezbollah-iran-syria-israel-lebanon.html.
8 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
9 Liz Sly, “How far could the dangerous endgame in eastern Syria go?” Washington Post, September 18, 2017,https://www.washingtonpost.com/news/worldviews/wp/2017/09/18/how-far-could-the-dangerous-endgame-in-eastern-syria-go/?utm_term=.1e7f9ac7f487.
10 Muhammed Hassan, “Iran Deepens Its Footprint in Deir Ez-Zor,” Chatham House, February 2018,https://syria.chathamhouse.org/research/iran-deepens-its-footprint-in-deir-ez-zor .
11 Makram Najmuddine, “Why Iran won’t leave Syria just yet,” Al Monitor, June 15, 2018, https://www.al-monitor.com/pulse/originals/2018/06/iran-israel-syria-russia-hezbollah-interests-realignment.html.
12 Seth Jones and Maxwell Markusen, “The Escalating Conflict with Hezbollah in Syria.
13 Anne Barnard, Ben Hubbard, and Isabel Kershner, “Iran, Deeply Embedded in Syria, Expands ‘Axis of Resistance’.”
14 Ephraim Kam, “The Iranian Military Intervention in Syria: A Look to the Future,” The Institute for National Security Studies, Strategic Assessment 20, no. 4 (January 2018), http://www.inss.org.il/publication/iranian-military-intervention-syria-look-future/.
15 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
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18 Babak Dehghanpisheh, “Special Report: The fighters of Iraq who answer to Iran,” Reuters, November 12, 2014,https://www.reuters.com/article/us-mideast-crisis-militias-specialreport/special-report-the-fighters-of-iraq-who-answer-to-iran-idUSKCN0IW0ZA20141112.
19Jack Moore, "Iranian Military Mastermind Leading Battle to Recapture Tikrit From ISIS," Newsweek, March 14, 2015, https://www.newsweek.com/iranian-military-mastermind-leading-battle-recapture-tikrit-isis-311516.
20 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East,” April 13, 2018,https://www.crisisgroup.org/middle-east-north-africa/gulf-and-arabian-peninsula/iran/184-irans-priorities-turbulent-middle-east.
21 Stratfor, “Iraq: The Battle for Tal Afar Begins,” August 20, 2017, https://worldview.stratfor.com/article/iraq-battle-tal-afar-begins#/entry/.
22 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
23 Liz Sly, “How far could the dangerous endgame in eastern Syria go?”
24 Muhammed Hassan, “Iran Deepens Its Footprint in Deir Ez-Zor.”
25Tim Arango, “Iran Dominates in Iraq After U.S. ‘Handed the Country Over’,” New York Times, July 25, 2017.https://www.nytimes.com/2017/07/15/world/middleeast/iran-iraq-iranian-power.html.
26International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
27 Michael Knights, “Countering Iran's Missile Proliferation in Yemen,” The Washington Institute for Near East Policy, November 8, 2017. https://www.washingtoninstitute.org/policy-analysis/view/countering-irans-missile-proliferation-in-yemen.
28 April Longley Alley, “The Killing of Former President Saleh Could Worsen Yemen’s War,” International Crisis Group, December 6, 2017, https://www.crisisgroup.org/middle-east-north-africa/gulf-and-arabian-peninsula/yemen/killing-former-president-saleh-could-worsen-yemen-war.
29Joost Hiltermann and April Longeley Alley, “The Houthis Are Not Hezbollah,” Foreign Policy, February 27, 2017,https://foreignpolicy.com/2017/02/27/the-houthis-are-not-hezbollah/.
30 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
31 Ambassador Nikki Haley, U.S. Permanent Representative to the United Nations, “Ambassador Haley on the Release of the UN Report Identifying Iranian Violations,” U.S. Mission to the United Nations, February 15, 2018,https://usun.state.gov/remarks/8310.
32 Hani Al Sufayan, “Houthi militias attack southern Saudi border,” Al Arabiya English, November 30, 2017.https://english.alarabiya.net/en/News/gulf/2017/11/30/Houthi-militias-attack-southern-Saudi-border.html.
33Ben Hubbard, “Plight of Houthi Rebels Is Clear in Visit to Yemen’s Capital,” New York Times, November 26, 2016,https://www.nytimes.com/2016/11/26/world/middleeast/houthi-rebels-yemen.html.
34 Middle East Media Research Institute (MEMRI), MEMRI TV, “Footage of Houthi Underground Missile Launching Pads.” July 4, 2018, https://www.memri.org/tv/houthi-underground-missile-launching-pads/transcript.
35Ambassador Nikki Haley, U.S. Permanent Representative to the United Nations, “Remarks at a UN Security Council Briefing on Iran,” U.S. Mission to the United Nations, December 19, 2017,https://usun.state.gov/remarks/8227.
36Panel of Experts on Yemen, United Nations Security Council, “Final Report of the Panel of Experts on Yemen,” January 26, 2018. https://www.securitycouncilreport.org/atf/cf/%7b65BFCF9B-6D27-4E9C-8CD3-CF6E4FF96FF9%7d/s_2018_68.pdf.
37 Ambassador Nikki Haley, U.S. Permanent Representative to the United Nations, “Remarks at a Press Conference on Iranian Arms Exports,” U.S. Mission to the United Nations, December 14, 2017.https://usun.state.gov/remarks/8215.
38Courtney Kube, “U.S. Officials: Iran Supplying Weapons to Yemen's Houthi Rebels,” NBC News. October 27, 2016,https://www.nbcnews.com/news/us-news/u-s-officials-iran-supplying-weapons-yemen-s-houthi-rebels-n674181.
39 Middle East Media Research Institute (MEMRI), MEMRI TV, “Houthi Leader: We Have Developed Drones, Missiles that Reach Beyond Riyadh,” February 10, 2017, https://www.memri.org/tv/houthi-leader-we-have-developed-drones-missiles-reach-beyond-riyadh.
40 U.S. Ambassador Barbara Leaf, “Yemen Is Not a Sideshow,” The Atlantic, June 12, 2018,https://www.theatlantic.com/international/archive/2018/06/yemen-trump-iran-saudi-arabia-salman-uae/562571/.
41 Amir Toumaj, “Death of a General: What Shaban Nasiri Reveals About Iran’s Secretive Qods Force.”
42Anne Barnard, Ben Hubbard, and Isabel Kershner, “Iran, Deeply Embedded in Syria, Expands ‘Axis of Resistance’,”New York Times, February 19, 2018, https://www.nytimes.com/2018/02/19/world/middleeast/iran-syria-israel.html.
43 U.S. Ambassador Barbara Leaf, “Yemen Is Not a Sideshow.”
44 Matthew Levitt, “Hezbollah’s Pivot Toward the Gulf,” CTC Sentinel 9, Issue 8 (August 2016),https://ctc.usma.edu/hezbollahs-pivot-toward-the-gulf/.
45Ben Hubbard, “Iran Out to Remake Mideast With Arab Enforcer: Hezbollah.”
46 Matthew Levitt, “Hezbollah's Growing Threat Against U.S. National Security Interests in the Middle East,”Testimony for the House Foreign Affairs Subcommittee on the Middle East and North Africa, March 22, 2016,https://www.washingtoninstitute.org/policy-analysis/view/hezbollahs-growing-threat-against-u.s.-national-security-interests-in-the-m.
47 Middle East Media Research Institute (MEMRI), MEMRI TV, “Abu Mahdi Al-Muhandis, Deputy Commander of the Popular Mobilization Units: Optimism over Liberation of Mosul Was Exaggerated; No Objection to Russian Military Intervention in Syria; After Mosul, We Will Enter Syria; Hizbullah Trained Us against the Americans after 2003,” January 2, 2017, https://www.memri.org/tv/abu-mahdi-al-muhandis-deputy-commander-popular-mobilization-units-optimism-over-liberation-mosul.
48 David Daoud, “Hezbollah fighters train Iraqi Shiite militants near Mosul,” Long War Journal, November 5, 2016,https://www.longwarjournal.org/archives/2016/11/hezbollah-fighters-train-iraqi-shiite-militants-near-mosul.php.
49 Philip Issa, “Iraqi, Lebanese militias deploy to Syria’s Aleppo,” Associated Press, August 8, 2016,https://apnews.com/e9ac4c6a38614b82a3c8a0305f7e0d3b.
50Martin Chulov and Kareem Shaheen, “Sectarian fighters mass for battle to capture east Aleppo,” The Guardian,September 29, 2016, https://www.theguardian.com/world/2016/sep/29/aleppo-attack-foreign-syrian-fighters-plan-shia-islamic.
51Aymenn Jawad Al-Tamimi, “Quwat al-Ridha: Syrian Hezbollah,” Syria Comment, July 31, 2015,http://www.aymennjawad.org/17665/quwat-al-ridha-syrian-hezbollah.
52Phillip Smyth, “The Shiite Jihad in Syria and Its Regional Effects,” The Washington Institute for Near East Policy,February 2015, https://www.washingtoninstitute.org/policy-analysis/view/the-shiite-jihad-in-syria-and-its-regional-effects.
53Sune Engel Rasmussen and Zahra Nader, “Iran covertly recruits Afghan Shias to fight in Syria,” The Guardian, June 30, 2016. https://www.theguardian.com/world/2016/jun/30/iran-covertly-recruits-afghan-soldiers-to-fight-in-syria.
54 Ali Alfoneh, “Shia Pakistani Fighters in Syria,” Atlantic Council , April 26, 2017,http://www.atlanticcouncil.org/blogs/syriasource/shia-pakistani-fighters-in-syria.
55 Babak Dehghanpisheh, “Iran recruits Pakistani Shi'ites for combat in Syria,” Reuters, December 10, 2015.https://www.reuters.com/article/us-mideast-crisis-syria-pakistan-iran-idUSKBN0TT22S20151210.
56 Laila Bassam and Angus McDowall, “Syrian army, allies, take last IS stronghold in Syria: commander,” Reuters,November 8, 2017, https://www.reuters.com/article/us-mideast-crisis-islamic-state/syrian-army-encircles-last-is-stronghold-in-syria-al-manar-idUSKBN1D81NM.
57 Makram Najmuddine, “Why Iran won’t leave Syria just yet.”
58Chris Kozak, “Russia-Syrian-Iranian Coalition Seizes ISIS-Held Palmyra,” Institute for the Study of War, March 27, 2016. http://www.understandingwar.org/backgrounder/russian-syrian-iranian-coalition-seizes-isis-held-palmyra.
59 Ben Hubbard, “Iran Out to Remake Mideast With Arab Enforcer: Hezbollah.”
60 Anne Barnard, Ben Hubbard, and Isabel Kershner, “Iran, Deeply Embedded in Syria, Expands ‘Axis of Resistance’.”
61Mona Alami, “Hezbollah's war in Aleppo: Victory at any cost, even to civilians,” Middle East Eye, February 9, 2017,https://www.middleeasteye.net/news/hezbollahs-aleppo-victory-any-cost-1412427712.
62Seth Jones and Maxwell Markusen, “The Escalating Conflict with Hezbollah in Syria.”
63 Qassim Abdul, "Iraqi commander slams US, hails Iran in fight against ISIS in Tikrit," Christian Science Monitor, March 14, 2015, https://www.csmonitor.com/World/Middle-East/2015/0314/Iraqi-commander-slams-US-hails-Iran-in-fight-against-ISIS-in-Tikrit.
64 Nour Samaha, “Hezbollah’s Crucible of War,” Foreign Policy, July 17, 2016,https://foreignpolicy.com/2016/07/17/hezbollahs-crucible-of-war/.
65Ben Hubbard, “Plight of Houthi Rebels Is Clear in Visit to Yemen’s Capital.”
66 Nicholas Blanford, “Hezbollah’s Evolution: From Lebanese Militia to Regional Player,” Middle East Institute,November 28, 2017, http://www.mei.edu/content/hezbollah-s-evolution-lebanese-militia-regional-player.
67 Seth Jones and Maxwell Markusen, “The Escalating Conflict with Hezbollah in Syria.”
68 Dana Khraiche, “Hezbollah-Led Alliance Emerges Most Powerful From Lebanon Vote,” Bloomberg News, May 7, 2018, https://www.bloomberg.com/news/articles/2018-05-07/hezbollah-led-alliance-emerges-most-powerful-from-lebanon-vote.
69 Reuters, “Factbox: Hezbollah and allies gain sway in Lebanon parliament,” May 22, 2018,https://www.reuters.com/article/us-lebanon-election-parliament-factbox/factbox-hezbollah-and-allies-gain-sway-in-lebanon-parliament-idUSKCN1IN1OJ.
70Colin Clarke, “How Hezbollah Came to Dominate Information Warfare.” RAND Corporation, September 19, 2017,https://www.rand.org/blog/2017/09/how-hezbollah-came-to-dominate-information-warfare.html.
71 Amir Toumaj, “Death of a General: What Shaban Nasiri Reveals About Iran’s Secretive Qods Force.”
72 Michael Eisenstadt and Michael Knights, “Mini-Hezbollahs, Revolutionary Guard Knock-Offs, and the Future of Iran’s Militant Proxies in Iraq,” War on the Rocks, May 9, 2017, https://warontherocks.com/2017/05/mini-Hezbollahs-revolutionary-guard-knock-offs-and-the-future-of-irans-militant-proxies-in-iraq/.
73 Andrew England, “Iraq’s Shia Militias: Capturing the State,” Financial Times, July 31, 2018,https://www.ft.com/content/ba4f7bb2-6d4d-11e8-852d-d8b934ff5ffa.
74 Michael Eisenstadt and Michael Knights, “Mini-Hezbollahs, Revolutionary Guard Knock-Offs, and the Future of Iran’s Militant Proxies in Iraq.”
75 Phillip Smyth, “Iranian Militias in Iraq's Parliament: Political Outcomes and U.S. Response,” The Washington Institute for Near East Policy, June 11, 2018, https://www.washingtoninstitute.org/policy-analysis/view/iranian-militias-in-iraqs-parliament-political-outcomes-and-u.s.-response.
76 International Crisis Group, “Iraq’s Paramilitary Groups: The Challenge of Rebuilding a Functioning State,” July 30, 2018. https://www.crisisgroup.org/middle-east-north-africa/gulf-and-arabian-peninsula/iraq/188-iraqs-paramilitary-groups-challenge-rebuilding-functioning-state.
77 Andrew England, “Iraq’s Shia Militias: Capturing the State.”
78 Bruce Riedel, “Yemen war escalates as Houthis threaten UAE, Saudi Arabia,” Al Monitor, July 29, 2018,https://www.al-monitor.com/pulse/originals/2018/07/yemen-war-houthis-saudi-arabia-escalates.html.
79 April Longley Alley, “The Killing of Former President Saleh Could Worsen Yemen’s War.”
80 Joost Hiltermann and April Longeley Alley, “The Houthis Are Not Hezbollah.”
81 International Crisis Group, “Prospect of Talks and Threat of Escalation Both Rise in Yemen,” May 15, 2018,https://www.crisisgroup.org/middle-east-north-africa/gulf-and-arabian-peninsula/yemen/prospect-talks-and-threat-escalation-both-rise-yemen.
82 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
84Renad Mansour and Faleh Jabar, “The Popular Mobilization Forces and Iraq’s future,” Carnegie Endowment for International Peace, April 28, 2017, http://carnegie-mec.org/2017/04/28/popular-mobilization-forces-and-iraq-s-future-pub-68810.
85 Garrett Nada and Mattisan Rowan, “Pro-Iran Militias in Iraq.”
86 Renad Mansour and Faleh Jabar, “The Popular Mobilization Forces and Iraq’s future.”
87 Garrett Nada and Mattisan Rowan, “Pro-Iran Militias in Iraq.”
89 Aymenn Jawad Al-Tamimi, “Quwat al-Ridha: Syrian Hezbollah.”
90Ali Alfoneh, “Shia Afghan Fighters in Syria,” Atlantic Council , April 19, 2017,http://www.atlanticcouncil.org/blogs/syriasource/shia-afghan-fighters-in-syria.
91Phillip Smyth, “The Shiite Jihad in Syria and Its Regional Effects.”
92 Ali Alfoneh, “Shia Pakistani Fighters in Syria.”
93Babak Dehghanpisheh, “Iran recruits Pakistani Shi'ites for combat in Syria.”
94 Aymenn Jawad Al-Tamimi, “Liwa al-Mukhtar al-Thiqfi: Syrian IRGC Militia,” Syria Comment. March 08, 2017,https://www.meforum.org/articles/2017/liwa-al-mukhtar-al-thiqfi-syrian-irgc-militia.
95 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
96 Joost Hiltermann and April Longeley Alley, “The Houthis Are Not Hezbollah.”
97 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
98Stephen Walt, The Origin of Alliances, (Ithaca: Cornell University Press, September 1990): vi, 18-25.
99 Jakub Grygiel. “Arming Our Allies: The Case for Offensive Capabilities.” Parameters 45, 3, Autumn 2015, 39–49.
100 Stephen Walt. The Origin of Alliances.
101 Anthony Cordesman. “Iran’s Rocket and Missile Forces and Strategic Options.” Center for Strategic and International Studies, October 27, 2014, https://csis-prod.s3.amazonaws.com/s3fs-public/legacy_files/files/publication/141007_Iran_Rocket_Missile_forces.pdf.
102 Michael Eisenstadt, “The Role of Missiles in Iran's Military Strategy.” The Washington Institute for Near East Policy, November 2016. https://www.washingtoninstitute.org/policy-analysis/view/the-role-of-missiles-in-irans-military-strategy.
103 Amir Toumaj, “Death of a General: What Shaban Nasiri Reveals About Iran’s Secretive Qods Force.”
104 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.””
105 Seth Jones and Maxwell Marcusen, “The Escalating Conflict with Hezbollah in Syria.”
106 International Crisis Grou, “Iran’s Priorities in a Turbulent Middle East.”
107 Islamic Republic News Agency, “Iraq is Iran’s ‘strategic depth’: Army commander,” March 8, 2018.http://www.irna.ir/en/News/81533347.
108 Tim Arango, “Iran Dominates in Iraq After U.S. ‘Handed the Country Over’.”
109Philip Issa, “Iraqi, Lebanese militias deploy to Syria’s Aleppo.”
110 Garrett Nada and Mattisan Rowan, “Pro-Iran Militias in Iraq.”
111 Yoel Guzansky and Eldad Shavit, “Yemen after Saleh: Microcosm of a Regional Struggle,” The Institute for National Security Studies , INSS Insight No. 998, December 14, 2017, http://www.inss.org.il/publication/yemen-saleh-microcosm-regional-struggle/.
112 Sima Shine, “Iran and its Rivals: A Strategic Balance Sheet,” The Institute for National Security Studies, 2018,http://www.inss.org.il/publication/iran-rivals-strategic-balance-sheet/.
113 Middle East Media Research Institute (MEMRI), MEMRI TV, “Houthi Military Spokesman Threatens to Target U.S., French, Other Ships Entering Yemeni Territorial Waters,” February 5, 2017,https://www.memri.org/tv/houthi-military-spokesman-threatens-target-us-french-other-ships-entering-yemeni-territorial.
114 Garrett Nada and Mattisan Rowan, “Pro-Iran Militias in Iraq.”
115 Phillip Smyth, “The Shiite Jihad in Syria and Its Regional Effects.”
116 Babak Dehghanpisheh, “Iran recruits Pakistani Shi'ites for combat in Syria.”
117 Aymenn Jawad Al-Tamimi, “Liwa al-Mukhtar al-Thiqfi: Syrian IRGC Militia.”
118 Michael Eisenstadt and Michael Knights, “Mini-Hezbollahs, Revolutionary Guard Knock-Offs, and the Future of Iran’s Militant Proxies in Iraq.”
119 Tom Porter, “Iran, Israel, HAMAS, and Hezbollah: How the Islamic Republic is Shoring Up Relations Between Israel’s Enemies,” Newsweek, September 23, 2017, https://www.newsweek.com/iran-seeking-rebuild-ties-between-two-israels-most-bitter-enemies-670028.
120 Garrett Nada and Mattisan Rowan, “Pro-Iran Militias in Iraq.”
121 Dror Michman and Yael Mizrahi-Arnaud, “Iran’s dire, yet (for now) navigable straits,” The Brookings Institution,July 25, 2018, https://www.brookings.edu/blog/order-from-chaos/2018/07/25/irans-dire-yet-for-now-navigable-straits/.
122 International Crisis Group, “Iran’s Priorities in a Turbulent Middle East.”
126 Middle East Media Research Institute (MEMRI), MEMRI TV, “Abu Mahdi Al-Muhandis, Deputy Commander of the Popular Mobilization Units: Optimism over Liberation of Mosul Was Exaggerated; No Objection to Russian Military Intervention in Syria; After Mosul, We Will Enter Syria; Hizbullah Trained Us against the Americans after 2003.”
127 Tom Porter, “Iran, Israel, HAMAS, and Hezbollah: How the Islamic Republic is Shoring Up Relations Between Israel’s Enemies.”
128 Maren Koss, “Flexible Resistance: How Hezbollah and Hamas Are Mending Ties,” Carnegie Middle East Center, July 11, 2018, https://carnegie-mec.org/2018/07/11/flexible-resistance-how-hezbollah-and-hamas-are-mending-ties-pub-76782.
129 Shane Harris, Souad Mekhennet, and Missy Ryan, “In Bahrain, a smoldering insurgency reveals the resilience of Iran’s proxy war,” Washington Post, May 18, 2018, https://www.washingtonpost.com/world/national-security/in-bahrain-a-smoldering-insurgency-reveals-the-resilience-of-irans-proxy-war/2018/05/17/f107d684-4c7f-11e8-84a0-458a1aa9ac0a_story.html?utm_term=.75e817025c38.
130 Michael Knights and Matthew Levitt, “The Evolution of Shia Insurgency in Bahrain.” CTC Sentinel, January 2018, https://www.washingtoninstitute.org/policy-analysis/view/the-evolution-of-shia-insurgency-in-bahrain.
131 Joost Hiltermann and April Longley Alley, “The Houthis Are Not Hezbollah.”
132 Scott Worden, “Iran and Afghanistan’s Long, Complicated History,” U.S. Institute for Peace, June 14, 2018.https://www.usip.org/publications/2018/06/iran-and-afghanistans-long-complicated-history.
133 Ali Alfoneh, “Shia Afghan Fighters in Syria.”
134 Maria Abi-Habib and Mohammed al-Kibsi, “Al Qaeda Fights on Same Side as Saudi-Backed Militias in Yemen,Wall Street Journal, July 16, 2015, https://www.wsj.com/articles/al-qaeda-fights-on-same-side-as-saudi-backed-militias-in-yemen-1437087067.