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The Cruise Missile Defence Challenge: Doctrinal Reflections on the Subsonic, Supersonic, and Hypersonic Era
Muhammad Waqas Haider
Analysis Series
Analysis//0015/May/2026/London-Dialogue. 03 May 2026
Introduction
The cruise missile is no longer a marginal weapon system. Across the past decade, in conflicts as varied as the Russo-Ukrainian war, the Houthis’ campaign in the Red Sea, and the May 2025 Pakistan-India air engagement, cruise missiles have become the principal instrument through which states project precision and destructive power against defended targets. Yet the doctrinal and architectural response to this threat has lagged behind its operational reality. This article argues that effective cruise missile defence in the contemporary era requires a tiered analytical framework that distinguishes between subsonic, supersonic, and emerging hypersonic threats, recognises the structural advantages each holds over current defensive architectures, and accepts that no single procurement decision or system upgrade can substitute for the integration of detection, interception, hardening, and operational resilience.
The Subsonic Tier: Persistence Through Mass and Stealth
Subsonic cruise missiles, typically operating in the Mach 0.6 to Mach 0.9 range, remain the most widely employed tier of the cruise missile inventory globally. The American Tomahawk, the Russian Kalibr and Kh-101 families, the Pakistani Babur Hatf-VII, and the Indian French-made SCALP-EG all fall within this category. Their operational utility derives less from speed than from a combination of range, terrain-following flight profile, low radar cross-section, and the ability to be employed in saturating numbers. The Russian campaign against Ukrainian infrastructure since 2022 has demonstrated this saturating logic at industrial scale, with Russian cruise missile salvoes regularly exceeding the engagement capacity of layered Ukrainian defences.
For air defence planners, the subsonic threat is best understood as a defeat-by-volume challenge rather than a defeat-by-velocity one. Individual subsonic cruise missiles are within the engagement parameters of most modern medium-range systems, including the IRIS-T SLM, which has demonstrated high effectiveness against Russian Kh-101 cruise missiles in Ukrainian service. The doctrinal challenge is the depletion of interceptor inventory under sustained attack and the cost ratio between a few-hundred-thousand-dollar cruise missile and a one-to-three-million-dollar interceptor. The Centre for Strategic and International Studies has identified this asymmetry as one of the defining problems of contemporary air defence economics.
The Supersonic Tier: Where the Engagement Geometry Breaks Down
The supersonic tier, dominated by missiles operating at Mach 2.5-3.5, poses a qualitatively different defensive challenge. The Indo-Russian BrahMos, derived from the Russian P-800 Oniks, is the most operationally mature member of this class. Its baseline air-launched variant, the BrahMos-A, sustains speeds between Mach 2.8 and Mach 3.0 across the engagement profile, executes terminal manoeuvres at low altitude, and incorporates electronic counter-countermeasures designed against modern fire-control radars. The forthcoming BrahMos-NG, 50% lighter than its predecessor and equipped with an active electronically scanned array seeker with a further reduced radar cross-section and broader platform compatibility, including the indigenous Tejas Light Combat Aircraft.
The defensive challenge against supersonic cruise missiles is fundamentally one of compressed engagement geometry. A target at 30-50 metres altitude, moving at 1 kilometre per second, enters the radar horizon of a typical ground-based search radar at a range that yields an engagement window of approximately 15 to 20 seconds, depending on terrain and positioning. Within this window, the defending system must complete classification, fire control, launch, and intercept against a target whose terminal velocity exceeds the closing speed of most surface-to-air missiles. This is not a deficiency of any specific system; it is a structural constraint that confronts every air defence architecture currently in service, from the US Patriot PAC-3 to the Russian S-400 to the Chinese-origin HQ-9 family. Saudi Arabia’s experience with Houthi cruise missile and drone strikes against oil infrastructure, despite its substantial Patriot inventory, demonstrates the same lesson. The ongoing regional confrontations involving Iran, Israel, and the United States further demonstrate the difficulty of maintaining consistently high interception effectiveness against increasingly sophisticated and coordinated aerial attack profiles.
The May 2025 India-Pakistan conflict provided the most empirically detailed open-source case study of supersonic cruise missile employment between near-peer adversaries. Independent analysis by the Centre d’Histoire et de Prospective Militaires (CHPM) records that BrahMos strikes from Su-30MKI platforms targeted multiple Pakistani air bases during the conflict, while Pakistani retaliatory strikes employed indigenous precision strike weapons against Indian air bases and air defence sites, including the BrahMos depot at Beas. Both sides demonstrated that supersonic and subsonic cruise missiles, employed against comparably modern integrated air defence architectures, can achieve operational penetration against valuable targets. This bidirectional finding is the central empirical contribution of the conflict to the broader cruise missile defence literature.
The Hypersonic Tier: A Doctrinal Discontinuity
The forthcoming hypersonic tier represents a doctrinal discontinuity rather than an incremental progression. The BrahMos-II programme, jointly developed by India’s DRDO and Russia’s NPO Mashinostroyeniya, is projected to achieve speeds between Mach 7 and Mach 8 using scramjet propulsion, with a range of 1,500 kilometres and a targeted induction date around 2031. India’s parallel ET-LDHCM programme under Project Vishnu, successfully tested in July 2025, targets similar speeds with extended ranges to 2,500 kilometres. DRDO’s demonstration of sustained scramjet combustion for over 1,000 seconds in April 2025 represents a significant technical milestone and indicates that the operational timeline for these systems is no longer purely theoretical.
For air defence doctrine, hypersonic cruise missiles introduce challenges that current architectures were not designed to address, as existing systems were developed primarily for traditional threats and struggle to cope with emerging high-speed, manoeuvring weapons. At Mach 7, the engagement window between detection and impact for a target one hundred kilometres away is approximately forty-five seconds, even before accounting for the effects of plasma sheath formation on radar tracking and the manoeuvrability that scramjet-powered weapons can sustain at terminal phases. As Indian defence analysis itself acknowledges, no existing operational defence system can reliably intercept such weapons. The doctrinal implication is that hypersonic cruise missile defence cannot be built on the logic of point interception alone. It will require pre-launch detection through space-based and forward-deployed sensors, kinetic and non-kinetic engagement of launch platforms, and a fundamentally different conception of what constitutes adequate force protection for high-value targets.
A Tiered Doctrinal Framework
The cumulative implication of this analysis is that effective cruise missile defence in the contemporary era requires a tiered doctrinal framework matched to the threat tier. Against subsonic threats, the binding constraint is interceptor inventory and cost sustainability; the answer lies in dense mid-tier coverage, exemplified by IRIS-T SLM and CAMM-ER class systems whose unit economics permit sustained engagement against saturating attacks. Against supersonic threats, the binding constraint is engagement geometry; the answer lies in elevated and persistent sensor coverage that extends the detection horizon beyond what ground-based radars alone can achieve. Against emerging hypersonic threats, the binding constraint is fundamental engagement physics; the answer requires investment in pre-launch detection, left-of-launch options, and the systematic incorporation of passive defence including hardening and dispersal as a doctrinal partner to active interception.
Pakistan’s post-conflict trajectory, including reported evaluation of European mid-tier systems and continuing investment in indigenous capability through the Babur and Ra’ad programmes, reflects an emerging recognition of this tiered logic. The Pakistan Air Force enters the second year after the May 2025 conflict from a position of demonstrated operational competence, with a Saab Erieye AEW&C fleet that provides a strong foundation for enhanced sensor coverage and an integrated data link architecture that can accommodate additional layers. The doctrinal task ahead is the systematic integration of these capabilities against a threat picture that will continue to evolve toward higher speeds, lower signatures, and greater operational complexity.
Conclusion
The cruise missile defence challenge is one of the defining doctrinal problems of contemporary air warfare, and its difficulty is not unique to any single national context. The May 2025 India-Pakistan conflict, the Russian campaign in Ukraine, and the Houthi engagements in the Red Sea collectively demonstrate that current defensive architectures, across every major military tradition, are stressed by modern subsonic and supersonic threats and will be more profoundly challenged by the hypersonic systems now in advanced development. The doctrinal response demands tiered thinking, integrated architecture, and the institutional discipline to invest in detection, dispersal, and resilience alongside high-end interception. For practitioners and planners on the anniversary of an event that revealed the scale of the challenge, the question is not whether the cruise missile threat will intensify but whether doctrine and architecture are adapting fast enough to meet what is already arriving.
Muhammad Waqas Haider is a research fellow at London Dialogue and a doctoral candidate in International Relations at Lancaster University. A Chevening Scholar and former officer in the Pakistan Air Force, he brings over 17 years of experience across defence, strategy, and policy. His research focuses on space security and diplomacy, the technology-driven transformation of warfare, and strategic competition in South Asia and the Middle East.
Muhammad Waqas Haider
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