From Air to Ground: Introducing SOF SEAD Using DRFM Jamming Published Feb. 1, 2024 By Maj Jonathan C. Garver Wild Blue Yonder, MAXWELL AIR FORCE BASE, Ala. -- The United States military has historically sought to nullify the effects of adversary radars and radar-guided weapons systems through airborne suppression of enemy air defenses (SEAD) tactics, including high-speed anti-radiation missile (HARM) employment and electronic attack (EA).[1] While the US Air Force celebrates highly effective SEAD aircraft such as the EF-105 Thunderchief, F-4G Wild Weasel, and EC-130H Compass Call, these venerable airframes operated in very different environments.[2] With China and Russia’s current abilities to contest or deny airborne operations, the effectiveness of airborne SEAD will likely be very limited in the current era of great power competition (GPC). The US should, therefore, look at ground-based special operations forces (SOF) SEAD, particularly using EA with digital radio frequency memory (DRFM) jamming. This will require the US military to develop doctrine, training, and tactics to perform ground-based SOF SEAD. THE PAST: AIRBORNE SEAD Both lethal (e.g., HARM) and non-lethal (e.g., EA, or jamming) forms of airborne SEAD have been critical to the success of past US aerial campaigns by enabling the U.S. to gain and maintain air superiority, providing the ability to freely maneuver, and inflicting material and psychological impacts on the enemy. The Vietnam War is often viewed as the watershed moment for SEAD. With equipment supplied mostly by the Soviet Union, the North Vietnam Army (NVA) had developed an integrated air defense system (IADS) to prevent U.S. airstrikes on critical infrastructure and logistics lines of communication (LOC). With most of the NVA’s surface-to-air missile (SAM) systems reliant on radar to acquire, track, and engage U.S. aircraft, the US identified their acquisition and tracking radars as critical nodes. To defeat them, the US employed EA aircraft such as the EF-105 and F-4Cs armed with radar-homing missiles and jamming equipment. Once the SAM sites were suppressed, U.S. strike aircraft were able to operate deep in enemy territory.[3] The US expanded its SEAD repertoire by developing dedicated SEAD aircraft, such as the Navy’s EA-6B Prowler, which later evolved into the EA-18G Growler, and the Air Force’s EC-130 Compass Call. These high-demand aircraft opened air corridors for U.S. fighters and bombers to penetrate enemy air defenses in Iraq, Kosovo, and Libya.[4] As the US military’s current SEAD doctrine and acquisition efforts have largely been shaped by campaigns in which the US had relatively uncontested control of the airspace, it is not adequately prepared for conventional operations with contemporary near-peer competitors. China and Russia have both fielded anti-access/area denial (A2/AD) systems, such as long-range SAMs (e.g., SA-20, SA-21, HQ-9) and anti-ship cruise missiles (ASCM), that can keep traditional U.S. SEAD aircraft at bay far beyond their borders.[5] For example, modern SAMs can simultaneously engage up to 80 targets from over 400 kilometers away.[6] Conversely, decades of complacency and underinvestment in EA have left the US ill-equipped to contend with these new threats. Having divested the EA-6B Prowler in 2019, the US Navy has only the EA-18G Growler to perform SEAD. The Air Force has not operated a dedicated airborne EA aircraft since it retired the EF-111A Raven in 1999, relying solely on its low-density, aging fleet of EC-130H Compass Calls.[7] While the EC-130H replacement, the modified Gulfstream EC-37B, is expected to reach initial operating capability (IOC) in 2026, it will face the same A2/AD challenges as its predecessor.[8] Although the F-35 is advertised to have a boutique EA capability, its size, speed, and multirole nature limit its effectiveness, which will be insufficient to handle the task load expected of a campaign-level SEAD asset in a war against China or Russia.[9] Rather than pour sunk costs into airborne SEAD, the U.S. military must seek a ground-based solution. THE FUTURE: SOF SEAD Excelling in the key components of SEAD, U.S. SOF is uniquely positioned to perform SEAD from the ground. To effectively suppress enemy radars, U.S. forces first depend on electronic information gathering and dissemination. Furthermore, effective SEAD campaigns require synchronized command and control (C2) and tight coordination between air and ground assets.[10] One of the core SOF activities is special reconnaissance, which is intelligence collection in “hostile, denied, or politically sensitive environments to collect or verify information of strategic or operational significance.”[11] U.S. SOF teams are trained to infiltrate contested areas and employ signals intelligence (SIGINT) equipment to characterize the battlespace. Furthermore, they can employ their 20-plus years of experience controlling joint fires in Iraq and Afghanistan to coordinate between air and ground elements. However, given the enemy’s A2/AD capabilities to push back air assets, in SOF SEAD, the SOF operators will also serve as the jamming platform. Using their ground-based jammer, the SOF operators will open the airspace for U.S. aircraft to enter. The SOF community’s longstanding mission of unconventional warfare will also facilitate ground-based SOF SEAD.[12] Pre-existing relationships with partner-nation intelligence services and resistance forces can provide placement and access (P&A) proximate to enemy IADS. For example, if the U.S. desired to strike enemy targets in an area heavily defended by long-range SAMs supported by an array of electronic protection (EP) measures, the use of airborne SEAD would have a high risk to force. Instead, plain-clothed U.S. SOF may use their unique authorities to liaise with neighboring country intelligence services or local resistance forces to facilitate crossing the border from allied territory into the target nation. Allied personnel could provide language, cultural, and terrain expertise to U.S. SOF, and accompany them to locations proximate to the hostile IADS. Once U.S. SOF had suppressed the target nation’s radars with their ground-based EA, it would be possible to launch direct airstrikes against the joint force commander’s (JFC) priority targets. The intelligence service or resistance force would then retrograde U.S. SOF back into friendly territory. THE MEANS: DRFM JAMMING SOF SEAD is best accomplished using DRFM jammers, which contain a transceiver capable of digitizing, recording to memory, modifying, and re-transmitting the recorded waveform. Upon receiving the modified signal, the target radar incorrectly deduces the friendly unit’s speed, bearing, range, or altitude based on the DRFM system’s manipulation.[13] As the jamming waveform is a modification of the target radar’s original signal, it must dupe the target radar into perceiving the re-transmitted signal as a coherent return rather than EA.[14] This false coherence allows DRFM jammers to defeat modern radars with advanced EP, which provides an advantage over other EA techniques, such as noise or repeater jamming. Their digital nature provides advantages in both speed and scale, as DRFM jammers can instantaneously adjust a signal’s power or frequency using software-defined systems rather than relying on analog means.[15] They can also modify the digitally-stored signal many times to employ various EA techniques, such as range gate pull-off (RGPO), velocity gate pull-off (VGPO), inverse-gain jamming, or false target generation against a single or multiple targets.[16] DRFM jamming equipment has both the portability and capability ideal for SOF SEAD. They are easy to conceal and transport with only a few modular parts, including analog-to-digital converters (ADC), field-programmable gate arrays (FPGA), processors, and transceivers.[17] This equipment can be form-fit to the size of a vehicle, which is ideal for SOF maneuvers. Second, DRFM jammers can replay a target radar’s pulses many times, saturating a SAM operator’s scope with false targets.[18] Since many modern SAMs are radar-guided and lack an optical tracking option, false target saturation is the ideal EA method to break lock on friendly aircraft. Finally, DRFM systems can create, modify, and transmit arbitrary waveforms digitally without ever receiving an emission from the target radar, nullifying the effectiveness of an adversary’s wartime reserve modes.[19] OPPORTUNITIES SOF SEAD using DRFM jamming provides some interesting capabilities. Thanks to their unique P&A capability, they can potentially target otherwise unattainable adversary IADS. With SOF teams being more maneuverable and difficult to engage than traditional airborne SEAD platforms, SOF SEAD reduces the risk of U.S. casualties. SOF SEAD also has the potential for non-attributable operations, especially when coupled with DRFM jamming, thereby decreasing the risk of political escalation or kinetic response. Finally, ground-based DRFM jamming is repeatable as adversaries have struggled to develop EP measures to defend against DRFM jamming due to the coherence associated with signal re-transmission.[20] Therefore, a SOF team can use its P&A to move quickly to a target, suppress the target radar, and egress safely to an area in the rear while maintaining the secrecy of ground-based SEAD tactics. LIMITATIONS SOF SEAD is not without its limitations. SOF SEAD would unlikely succeed in denied areas, especially ones in which a partner nation intelligence service does not maintain P&A. For example, it would be difficult for U.S. SOF to get within range of Chinese SAMs for DRFM jamming to be effective in mainland China due to the nature of China’s closed society, especially bolstered by its biometric and closed-circuit television (CCTV) network.[21] There is also the likelihood of capture and imprisonment for ground-based SEAD, but, as with most SOF operations, this can be mitigated through proper training and mission management. Furthermore, training for the SEAD mission set would require extensive resources (i.e. time and money), which could detract from training in traditional SOF missions such as direct action (DA) and foreign internal defense (FID). If SOF SEAD were [thankfully] never needed, this could be viewed by Congress as a misappropriation of resources. Finally, since SOF SEAD is optimized when facilitated by a liaison intelligence service, a foreign government could oppose the mission, possibly leaking it to U.S. adversaries. EMPLOYMENT RECOMMENDATIONS U.S. SOF can affect the battlespace throughout the various phases of SEAD operations. During the “Reconnaissance” phase, U.S. and liaison service SOF can perform close-access monitoring of the target.[22] Trained in myriad intelligence collection techniques, SOF can answer critical intelligence gaps for an IADS takedown mission, such as close-range photography and video recording, in the days before an IADS takedown. SOF P&A can provide high-resolution digital photos and videos unattainable through national (e.g., satellites) or theater (e.g., U-2, MQ-9, RQ-4, etc.) means. This collection will refine the U.S.’s understanding of the target’s pattern of life (PoL), which can be crucial to determining the best time of day to suppress the system. SOF can also use an electromagnetic spectrum (EMS) scanner, such as a Spectrum Guard, to evaluate radio frequency (RF) activity in the target area, allowing the SOF team to tailor their DRFM technique.[23] SOF can also leverage its P&A to place unattended ground sensors (UGS) near the target.[24] These leave-behind UGS would alert the US if any large, transporter-erector-launcher (TEL)-sized vehicles departed the area. Once the SOF team has assessed the enemy environment during the “Reconnaissance” phase, it is ready to suppress the system in the follow-on “Buzzer On” phase to allow either an airstrike or unimpeded overflight of U.S. aircraft. As U.S. aircraft approach the target area, the SOF team will call “Buzzer On,” indicating that the DRFM system has been activated.[25] The inbound aircraft would monitor their radar warning receivers (RWR) for SAM indications, feeding this information back to the SOF team so they can adjust their DRFM technique if needed. As the aircraft flies over the suppressed SAM, the intelligence member(s) of the SOF team would collect communications intelligence (COMINT) to identify the enemy’s primary, alternate, contingency, and emergency (PACE) communications plan. They will also perform ground-based electronics intelligence (ELINT) to identify, record, and disseminate any wartime reserve modes that are observed when the SAM experiences real-world EA, which can be valuable to U.S. Operational Plan (OPLAN) development for large-scale combat operations. After completing their jamming operations, the SOF team can enter the BDA” (battle damage assessment) phase. (Although the term “BDA” implies a kinetic strike on an enemy SAM, the concepts apply to any type of mission or target.) If possible, the team can maneuver to a different position of advantage to avoid detection once the DRFM jammer is switched off. Most importantly, the U.S. SOF team would determine whether or not the SAM had been suppressed. If so, the team can perform post-mission reconnaissance, sensitive site exploitation (SSE), or exit the area to avoid detection to ensure that sensitive tradecraft techniques and equipment are concealed. If the SAM fails to be suppressed, the SOF team can immediately communicate with the airborne mission commander to determine if the SOF team should re-engage, cease operations and egress, or directly attack the target. Thus, SOF SEAD has the added advantage of being able to launch ground-based kinetic fires at the target to achieve the same effect, unlike their airborne counterparts. Ideally, though, this phase would focus heavily on intelligence collection, communication, and eventual egress from the target. CONCLUSION With modern adversaries such as China and Russia fielding robust A2/AD systems that outrange SEAD aircraft, the era of airborne SEAD driving a wedge through relatively uncontested airspace has come to an end. To overcome this challenge, the U.S. must develop ground-based SOF SEAD doctrine, training, and tactics using ground-based DRFM. By tapping into existing SOF skills and connections, SOF teams armed with DRFM jammers can provide a way to counter the seemingly impenetrable A2/AD systems. Although SOF SEAD may not be suitable for missions in denied areas, it has the unique capability of conducting kinetic attacks in the extreme case that their EA proves unsuccessful. While SOF SEAD through ground-based DRFM jamming does have its risks, it may be the key to overcoming modern A2/AD systems. Major Jonathan C. Garver Maj Garver is an intelligence officer assigned to the CENTCOM/J2 at MacDill AFB, Florida, where he leads 25 military and civilian personnel in formulating ISR strategies and conducting multi-discipline collection management for U.S. operations in 21 nations in the Middle East, Central Asia, and South Asia. His previous experience spans ISR, HUMINT, and most recently, intelligence support to special operations, during which he developed a deep interest in SOF SEAD. Maj Garver earned his BS from Penn State University and will earn his MPA from Cornell University in December 2024. This article originated as a paper for the EW and Cyberspace elective at Air Command and Staff College. NOTES [1]. James R. Brungess, Setting The Context: Suppression of Enemy Air Defenses and Joint Warfighting in an Uncertain World (Maxwell AFB, AL: Air University Press, 1994), 27. [2]. Ibid., 34. [3]. Colonel Joseph Speed and Lieutenant Colonel (ret.) Panagiotis Stathopoulos, “SEAD Operations of the Future: The Necessity of Jointness,” Joint Air Power Competence Center (JAPCC) Journal 26 (Spring/Summer 2018): 38-39, https://www.japcc.org/wp-content/uploads/JAPCC_J26_screen.pdf; William A. Hewitt, “Planting the Seeds of SEAD: The Wild Weasel in Vietnam” (master’s thesis, School of Advanced Airpower Studies, Maxwell AFB, AL, 1992), 23, 26-27. [4]. Speed and Stathopoulos, “SEAD Operations of the Future,” 39-40. [5]. John Toepher, “SEAD From the Ground Up: SOF’s Role in the Suppression of Enemy Air Defenses” (master’s thesis, Naval Postgraduate School, Monterey, CA, June 2019), 2. [6]. Ibid., 22. [7]. Brett Tingley and Tyler Rogoway, “Navy’s New Jamming Pods for EA-18 Growler Eyed for Air Force Fighters,” The War Zone, July 28, 2021, https://www.thedrive.com/the-war-zone/41727/navys-new-jamming-pods-for-ea-18g-growler-eyed-for-air-force-fighters. [8]. “EC-37B Compass Call,” Air and Space Forces Magazine, n.d., accessed 20 February 2023, https://www.airandspaceforces.com/weapons-platforms/ec-37b/. [9]. Loren Thompson, “The F-35 Isn’t Just ‘Stealthy’: Here’s How Its Electronic Warfare System Gives It An Edge,” Forbes Magazine, May 13, 2019, https://www.forbes.com/sites/lorenthompson/2019/05/13/how-a-super-agile-electronic-warfare-system-makes-f-35-the-most-invincible-combat-aircraft-ever/. [10]. Toepher, “SEAD From the Ground Up,” 23. [11]. Department of the Air Force, Special Operations, Air Force Doctrine Publication (AFDP) 3-05 (Maxwell AFB: LeMay Doctrine Center, 1 February 2020), 12. [12]. Ibid., 13. [13]. Kyle Davidson and Joey Bray, “Understanding Digital Radio Frequency Memory Performance in Countermeasure Design,” Applied Sciences 10, no. 12 (2020): 2, https://www.mdpi.com/2076-3417/10/12/4123/pdf?version=1592321290. [14]. Charles J. Watson, “A Comparison of DDS and DRFM Techniques in the Generation of ‘Smart Noise’ Jamming Waveforms” (master’s thesis, Naval Postgraduate School, Monterey, CA, September 1996), 71. [15]. Davidson and Bray, “Understanding Digital Radio Frequency Memory,” 1. [16]. Rajesh Uppal, “Digital Radio Frequency Memory (DRFM) Has Improved the Capability of Electronic Warfare and Anti-Missile Countermeasure Systems,” International Defense, Security, and Technology, February 20, 2019, https://idstch.com/technology/electronics/digital-radio-frequency-memory-drfm-improved-capability-electronic-warfare-anti-missile-countermeasure-systems/ . [17]. Davidson and Bray, “Understanding Digital Radio Frequency Memory,” 3. [18]. Uppal, “DRFM Has Improved.” [19]. “Introduction of Smart Jammers / Deceptive Jammers,” Dynamite Global Strategies, January 6, 2020, https://usdgs.com/introduction-of-smart-jammers-deceptive-jammers/. [20]. Antonio Zaccaron, “Digital Radio Frequency Memory (DRFM) for ECM Applications,” EMSOPEDIA, accessed 1 May 2023, https://www.emsopedia.org/entries/digital-radio-frequency-memory-drfm-for-ecm-applications/. [21]. Warren P. Strobel, “Biometrics, Smartphones, Surveillance Cameras Pose New Obstacles for U.S. Spies: U.S., rivals seek ways to adapt spycraft to a changing world; being on the grid can blow your cover, but so can staying off,” Wall Street Journal, November 27, 2021, https://www.wsj.com/articles/biometrics-smartphones-surveillance-cameras-pose-new-obstacles-for-u-s-spies-11638009002. [22]. Toepher, “SEAD From the Ground Up,” 36. [23]. “Spectrum Guard Pro: Unique Multi-Receiver Design Allows for Simultaneous Spectral, Wireless and/or Wi-Fi Evaluation,” CACI SystemWare website, accessed 1 May 2023, https://www.ctl-systemware.com/spectrum-guard-pro.html. [24]. Toepher, “SEAD From the Ground Up,” 32. [25]. John Keller, “Can U.S. air-to-air missiles stand up to modern enemy electronic warfare?,” Military & Aerospace Electronics Magazine, May 18, 2016, https://www.militaryaerospace.com/home/article/16709058/can-us-airtoair-missiles-stand-up-to-modern-enemy-electronic-warfare.