Iran Owns the Gray Zone

By Commander T. J. Gilmore, U.S. Navy

What Iran Wants

Iran is an anti–status quo state that seeks to establish itself as the Middle East hegemon and degrade U.S. influence in the region, because it views the United States as an existential threat. Iran’s fundamental goals include controlling strategic approaches, most notably the Strait of Hormuz, and influencing the Bab el-Mandeb and Levant. It also seeks to further the community of Shia Islam. To achieve these objectives, Iran exploits the gray zone where it relies primarily on surrogates, stand-off weapons, or a combination of these capabilities. The country prefers to avoid the high-intensity, conventional war that characterized its near decade-long conflict with Iraq but is willing to approach this area so long as ambiguity can exist.

Iran’s ability to spread its political influence and malign activity has accelerated because of civil wars in Syria and Yemen and the Islamic State’s temporary conquest of a significant portion of Iraq. But the character and purpose of the Islamic Republic of Iran’s current activity in the gray zone is not new and is firmly rooted in its historic malign behavior. The country’s military organization, weapons preference, and geography all contribute to its gray zone strategy.

Iran’s armed forces are organized to conduct terror, subversion, proxy operations, naval guerrilla warfare, and long-range strike operations. 3 Of these, the use of proxy forces—inexpensive, easily employed, and deniable—is preferred. Iran excels at ambiguity and knows it is unlikely to provoke a strong U.S. response. This fact is the prime mover of Iran’s gray zone strategy. Except for Operation Praying Mantis in 1988, in which the U.S. Navy attacked militarized Iranian oil platforms following the near-sinking of the USS Samuel B. Roberts (FFG-58) after she struck an Iranian mine, the United States has not responded forcefully to or imposed substantial cost on Iran because of its gray zone activity in the four decades since the 1979 Islamic revolution. 4

The Islamic Republic mastered uncomplicated, point-and-shoot missiles during its formative years that offer stand-off ranges against their targets. During the 1987–88 Tanker War, for example, Iran attacked 190 neutral ships from 31 nations using mostly rudimentary cruise missiles.5 Its missile technology has improved considerably since then, and Iran has expanded this gray zone firepower by transferring to proxy forces sophisticated missiles, unmanned systems, and other stand-off capabilities.

Iran’s geography and demographics also contribute to its gray zone effectiveness. Given the quantity and importance of the globally traded oil supply in the Middle East and international shipping transit routes, the world must come to Iran—or at a minimum, through areas in which Iran has significant influence: the maritime chokepoints in the Strait of Hormuz and Bab el-Mandeb. Iran’s overwhelming Shia Muslim population, along with sizable Shia populations in some of Iran’s neighbors, provides the scaffolding for gray zone activity, in a region where religious affiliation can be at least as important as national identity.

Iran operates a variety of ship and boat classes, including the U.S.-built escort frigate shown here alongside an armed patrol boat. Though the country's military uses proxy forces to achieve many of its strategic goals, it has improved its ability to project significant conventional power regionally.

Gray Zone Threats in the Maritime Domain

Current theater dynamics suggest Iran now has or will soon have more regional influence than at any time since the revolution, greatly expanding its defense-in-depth and power-projection capabilities. The recent working-class protests inside Iran show that, given widespread economic challenges, a measurable portion of the population questions the country’s regional adventurism. While displays of public discontent are rare in the Islamic Republic, they are unlikely to engender a retrenchment in Yemen or the Levant in the near term or affect Tehran’s ability to operate in the gray zone.

Notwithstanding the October 2000 al Qaeda attack on the USS Cole (DDG-67) in Aden, Yemen, U.S. Navy units in the southern Red Sea and Bab el-Mandeb until recently have operated routinely in a permissive environment. With Iranian support to Houthi rebels, that benign situation no longer exists. The Bab el-Mandeb (Arabic for “Gate of Tears”) is approximately ten miles wide at its narrowest point and has lived up to its name in the past two years as one of the most dangerous and unpredictable areas in which U.S. naval forces operate. The strategic chokepoint provides the critical link between the southern Red Sea and the Gulf of Aden, where more than 3 million barrels of oil pass daily, and Houthi forces have demonstrated an ability to leverage Iranian expertise in the maritime domain. 6

Antiship cruise missiles, mines, and unmanned surface vehicles (USVs) are all capabilities Iran has developed and proliferated to proxies in an area vital to global trade. On 1 October 2016, Houthi forces combined commercially available ship-tracking software, maritime spotters, and antiship cruise missiles to damage the Emirati-operated fast transport vessel Swift severely. Within days—on 9, 12, and 15 October—Houthi forces unsuccessfully fired cruise missiles at U.S. warships north of the Bab el-Mandeb. After the 12 October attack, the Navy conducted a limited Tomahawk strike to destroy several Houthi radar sites. In early 2017, unconfirmed reports surfaced of Houthi mining activity in the Bab el-Mandeb, and on 30 January 2017, the Saudi frigate Al Madinah was attacked by an explosives-laden USV. On 26 April, the Saudi Arabian coast guard disabled a USV that was approaching the Aramco Oil terminal in Jazan, Saudi Arabia, near the Yemen border.

Iran has assisted Houthi rebels with training, repurposing older surface-to-air missiles, improving ballistic-missile technology, and incorporating unmanned aerial vehicles (UAVs). After months of accusations at the highest levels of government, on 14 December 2017, the United States provided to the United Nations (UN) material evidence of Iranian support to the Houthis. 7 Iran has established a base of offensive operations and remains capable of projecting power in the Bab el-Mandeb, despite international efforts to enforce a UN weapons embargo. Also, the U.S. response to being fired on in the Bab el-Mandeb was insufficient to deter further malign action or restore naval freedom of movement.

In the eastern Mediterranean, U.S. naval forces have not been attacked with shore-based missiles or explosive USVs, as they have been near the Red Sea. Nonetheless, the operating environment has the potential to become less permissive as Iran assumes effective control of more ungoverned territory. Before the Swift video went viral, few expected that Houthi forces could conduct an antiship missile engagement in the Bab el-Mandeb; the eastern Mediterranean is the next area where Iranian surrogates could strike. While Lebanese Hezbollah remains the most capable Iranian proxy—demonstrating its proficiency in employing Iranian-supplied antiship missiles with its 2006 attack on the Israeli corvette Hanit—there are additional concerns in the Levant. Tehran controls a series of multinational Shia militias—the so-called Iran Foreign Legion—that stretch from the Zagros Mountains to the Israeli border. 8 These militias consist of tens of thousands of fighters, have access to advanced weaponry, and have worked under Iran’s Quds Force umbrella in the counter-ISIS fight. 9

West to the Levant

Tactical movements since the summer of 2017 show that Iran is working aggressively to establish its long-desired land bridge to the Mediterranean Sea through Shia-controlled areas of Iraq and Syria. If Tehran succeeds, for the first time since the Islamic Revolution, it would be unfettered in its ability to move arms and material from Iran to the Mediterranean Sea, by way of Iraq, Syria, and Lebanon. Israeli officials have highlighted their concern over a growing Iranian base in Syria and on 7 September 2017 launched airstrikes on a Syrian military compound that allegedly functioned as a training facility and warehouse for short- and medium-range missiles. 10

Estimates place Hezbollah’s existing number of missiles and rockets at around 150,000, and it is not hard to imagine them and the Iran Foreign Legion expanding their stockpile for deterrence or employing these weapons against U.S. and allied naval forces in the eastern Mediterranean once the land bridge is complete. These militia forces are fresh from the counter-ISIS fight and in search of employment. Iran is positioned to orchestrate deniable offensive actions to a level sufficient to inflict damage on the U.S. Navy, solidify Iranian influence, and restrict U.S. freedom of movement in the eastern Mediterranean without crossing a threshold that would trigger a conventional conflict.

Other aspects of the potential Iranian gray zone threat in the eastern Mediterranean deserve attention. The Islamic Republic is one of the world’s leading operators of UAVs, and it uses them extensively in its counter-ISIS campaign throughout Syria and Iraq for surveillance and strike missions. Iran also uses UAVs routinely for maritime domain awareness in the Persian Gulf, and often flies near U.S. Navy ships, including aircraft carriers. 11 It should not come as a surprise when Iranian UAVs begin flying in the eastern Mediterranean. Similarly, with access to Syrian ports, Iran could transfer its USV technology to Syrian-based proxies just as it did in Yemen. Such activity would force a significant adjustment in the U.S. operating posture in the eastern Mediterranean.

The future relationship between Iran and Russia and how these countries manage the post-ISIS Levant should also be of concern. Russia has supplied arms to Iran, and Russia and Iran have worked closely together to counter the United States in Syria. Given the countries’ mutual affinity for operating in the gray zone and their opposition to a U.S. presence in the region, the direction their security relationship will take requires monitoring. Both Russia and Iran will be involved centrally in Syria for the foreseeable future.

The threats facing the U.S. Navy in the Strait of Hormuz are the most well-understood of the areas in which Iran is capable of striking U.S. warships—giving Tehran a deterrent capability. Anything Iran can bring to bear in the maritime domain, including an impressive arsenal of coastal defense cruise missiles, it maintains at the entrance to the Persian Gulf through which 34 percent of the global crude oil exports move daily. 12 These threats include highly maneuverable small boats that can reach speeds of 40–50 knots and routinely harass U.S. warships, armed with millimeter-wave-seeking missiles. Iran has achieved a domestic production capability with its antiship missiles, making improvements in range, accuracy, and destructiveness to complement and replace Silkworm and C-802 antiship cruise missiles imported from China. 13 The country also continues to expand and improve a mine inventory that likely exceeds 3,000 devices. While Iran has made measurable improvements in blue water naval capabilities in the past ten years, its primary tactical edge—the centerpiece of the Islamic Republic’s defense doctrine—remains its ability to conduct naval guerrilla warfare in the restricted battlespace of the Strait of Hormuz and Persian Gulf.

Recognition Is Only the Beginning

The U.S. Navy needs to continue to train and prepare for battle scenarios in the Strait of Hormuz given Iran’s capabilities and the frequency with which U.S. ships transit the chokepoint. But the United States also should recognize that this is the least likely of the three areas where Iran could confront U.S. forces. While the Navy might prefer to replay Praying Mantis in the event of a conflict with Iran, that nation is pursuing alternate courses of action. A recent decrease in “unsafe and unprofessional” naval approaches by Iranian units since August 2017 is a welcome development, but this should be viewed in the context of Iran’s overall destabilizing actions in the gray zone and is too recent to have too much weight assigned to it. The next naval engagement with Iran likely will take place near the Bab el-Mandeb or the waters off the Levant, where surrogates, unmanned systems, and previously undisclosed shore-based missiles will feature prominently. The engagement will include an element of ambiguity regarding Tehran’s role and will, therefore, limit U.S. counteraction. In these areas, the United States is losing influence, and the U.S. Navy’s maneuver space is most at risk.

Recognizing that Iran is executing a regional strategy by leveraging the gray zone is just the first step in formulating a useful counterstrategy. To win, the Navy should order course changes in three key areas.

First, pursue organic intelligence, surveillance, reconnaissance, and targeting capabilities to operate confidently in contested chokepoints without joint enablers. This approach would allow fleet commanders to leverage the full range of autonomous systems on the maximum number of naval platforms and operate continuously at a faster search-to-kill cycle than gray zone adversaries.

Second, place greater emphasis on advancing electromagnetic maneuver warfare (EMW) concepts, training, and associated equipment to combat gray zone aggression from unmanned systems and shore-based missiles. Increased use of these weapons by surrogates, which the Navy should expect, only will intensify the complexity of maritime warfare in critical chokepoints in the short term. The Navy has furthered EMW since the concept’s inception, but additional work is needed to disrupt adversary kill chains more effectively and manage deception beyond disciplined emissions control (EmCon) procedures. EMW is more than just EmCon—a passive technique—with emphasis. EMW should allow the force to exploit the entire electromagnetic spectrum actively and passively and ultimately improve the fleet’s offensive capacity. Increased training without a corresponding increase in concepts and capability will not allow the Navy to meet its goals in this area.

Third, for the first time in decades, the Navy needs to demonstrate a willingness to punch back—harder—against Iranian surrogates to prevent further malign activity. For the past 40 years, Iran systematically has applied various measures short of high-order war to inflict damage on the United States and kill Americans, and the Islamic Republic entered 2018 with an enhanced ability to project power in the maritime domain. For the Navy to maintain its preeminence as the global maneuver force, it must not only recognize the threat Iran poses in key areas but make specific course changes as well.

1. Michael Mazarr, Mastering the Gray Zone: Understanding a Changing Era of Conflict (Carlisle Barracks, PA: United States Army War College Press, 2015), 1, 33.

2. Christopher Paul, “ Confessions of a Hybrid Warfare Skeptic ,” Small Wars Journal, 3 May 2016, 5–6, also addresses this issue, stating “In many instances, we’re stuck ‘shaping’ or ‘deterring’ while they are fighting and winning.” 

3. Michael Eisenstadt, The Strategic Culture of the Islamic Republic of Iran (Quantico, VA: Marine Corps University Press, November 2015), 30.

4. David B. Crist, “Gulf of Conflict: A History of U.S.-Iran Confrontation at Sea,” The Washington Institute for Near East Policy, Policy Focus 95, Summer 2009, 7. 

5. Ibid, 1.

6. Jay Solomon, “ Trump Placing Heavy Focus on Yemen in the Campaign to Counter Iran ,” Washington Institute for Near East Policy, Policy Watch 2876, 20 October 2017, 1.

7. Gordon Lubold and Farnaz Fassihi, “U.S. Displays Weaponry It Says Proves Iran’s Influence,” Wall Street Journal, 14 December 2017. .

8. Michael Knights, “ How to Contain and Roll Back Iranian-Backed Militias ,” Washington Institute for Near East Policy, Testimony Submitted to the House Foreign Affairs Subcommittee on Terrorism, Nonproliferation, and Trade, 4 October 2017, 1.

9. Borzou Daragahi, “ Inside Iran’s Mission to Dominate the Middle East ,” Buzzfeed News, 30 July 2017.

10. Raja Abdulrahim and Nancy Shekter-Porat, “ Israel Strikes Military Sites in Syria ,” Wall Street Journal, 7 September 2017.

11. In August, CNN reported two separate incidents where an Iranian Sadegh-1 unmanned aerial vehicle flew within 1,000 feet of the USS Nimitz (CVN-68) and 100 feet of a Nimitz-based F/A-18 Hornet. Barbara Starr and Ryan Browne, “ Iranian Drone Flies ‘Dangerously’ Close to U.S. Aircraft Carrier ,” CNN, 14 August 2017.

12. Office of Naval Intelligence, Iranian Naval Forces: A Tale of Two Navies (Washington, DC: Office of Naval Intelligence, February 2017), 23.

13. Ibid, 32.

Commander Gilmore was the senior intelligence officer on the USS George H. W. Bush (CVN-77) for its 2017 Operation Inherent Resolve deployment. He is currently a federal executive fellow at the RAND Corporation.



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