The Indo-Pacific region is at the cusp of a new missile age, driven by perceptions of rising insecurity. Short- to intermediate-range surface-to-surface missile systems are quickly proliferating in the region.1 While military planners and policymakers in the region may view these capabilities as essential to preserving peace and maintaining general deterrence, this proliferation could intensify already complex security dilemmas and heighten nuclear escalation risks in crises.
Contemporary geopolitical dynamics, including systemic competition between China and the United States, and worsening threat perceptions continue to drive substantial investments by regional states in a range of missile capabilities. Other structural shifts have influenced proliferation as well. Notably, after years of alleging Russian noncompliance, the United States left the 1987 Intermediate-Range Nuclear Forces (INF) Treaty in 2019. Washington is now pursuing new ground-launched missiles once again, with a focus on Asia. Action-reaction dynamics between North Korea and South Korea have further accelerated missile proliferation trends. These changes have received insufficient attention by regional policymakers as missile procurement plans have flourished in recent years. Moreover, though the majority of established and emerging missile capabilities in the region are conventional, the potential for these non-nuclear or, in some cases, dual-capable missile systems to intensify nuclear escalation risks has also gone underappreciated. Finally, the complete absence of any regional or subregional mechanisms of negotiated military restraint—never mind formal arms control arrangements—has allowed these trends to continue unabated. Together, these developments are detriments to strategic stability in Asia.
While systematic efforts to assess the risks stemming from missile proliferation in Asia remain limited, headlines from the region in recent years have underscored the drivers and consequences of proliferation. These include China’s firing of ballistic missiles over Taiwan in August 2022, North Korea’s unprecedentedly intense missile-launching campaigns in 2022 and 2023, South Korea’s demonstrations of novel missile capabilities in 2021, Japan’s debate in recent years over whether to procure missiles to hold at risk North Korean targets,2 Australia’s pursuit of long-range strike capabilities under the AUKUS arrangement, and Taiwan’s passing in 2021 of a supplementary defense budget focused on indigenously developed surface-to-surface missile capabilities.3 The United States, too, has stood up several research and development programs for new ground-launched missile capabilities, unencumbered by the erstwhile limitations of the INF Treaty.4 Among these states, missiles are seen as essential for both deterrence and warfighting.
The proliferation of missile capabilities in Asia accompanies a broader surge in regional defense spending since the 2010s (see figures 1 and 2).5 The primary pursuers of significant new missile capabilities in East Asia—Australia, China, Japan, North Korea, South Korea, Taiwan, and the United States—all perceive acute security challenges and see value in long-range strike capabilities for deterrence and conventional warfighting alike. Four of these—Australia, Japan, South Korea, and Taiwan—are U.S. partners, and all but Taiwan are beneficiaries of treaty-codified collective defense arrangements.6 Along with the United States, these partners have particular concerns about China’s regional ambitions and, with the exception of South Korea, are primarily pursuing missile capabilities to deter potential conventional military action against their interests by Beijing. South Korea, which has maintained a robust domestic missile development program since the second half of the Cold War, continues to primarily posture its forces to deter North Korean nuclear and conventional attacks, but over time it could take a more forward-leaning stance against China as well. A permeating, background concern for many of these allies continues to be long-term uncertainty about the reliability of the United States’ extended deterrence commitments—a concern that grew salient in 2017–2021 when former U.S. president Donald Trump sometimes pursued an unorthodox approach to alliances. For these allies, the acquisition of new strike capabilities, while complementary to existing U.S. capabilities in an alliance context, also hedges against an uncertain future.
Amid these drivers, structural conditions in Asia today are not propitious for formal negotiated restraint, including risk reduction, confidence building, and arms control. Unlike the conventional arms buildup that took place in Europe during the Cold War and culminated in negotiated arms reduction processes, the multipolar nature of the contemporary pursuit of missile capabilities in Asia complicates the prospects for ambitious, formal risk reduction and arms control measures. Moreover, the presence of multiple nuclear-armed states with advanced missile capabilities—China, North Korea, the United States, and even India, Pakistan, and Russia—further adds complexity. Finally, unlike the Cold War, the states at the center of contemporary missile proliferation dynamics in Asia do not participate in regional collective defense arrangements like the North Atlantic Treaty Organization (NATO) and the erstwhile Warsaw Pact. While these types of arrangements are not essential to pursuing negotiated restraint, the Cold War condition of bipolarity limited the complexity of potential negotiations. Asia’s multipolar reality today complicates the task of achieving negotiated and verifiable restraint. The United States maintains its traditional hub-and-spoke alliance architecture in Asia through bilateral treaty arrangements with Australia, Japan, and South Korea and more diffuse commitments to Taiwan. While China and North Korea maintain a collective defense arrangement, which was first codified in 1961, their relationship is one of strained alignment7—especially as far as nuclear matters are concerned. Other states in the region pursue varied strategies of alignment, and many seek to preserve their strategic autonomy.
The trend toward missile proliferation in East Asia is unlikely to soon be reversed, but it is imperative that regional decisionmakers fully understand the scope of potential escalation risks and, out of an interest in averting nuclear war, work to limit these risks.
Given these complications, the tractability of missile-focused risk reduction efforts or arms control may appear questionable. While there are substantial obstacles to formalized arms control arrangements in the region, current trends if left unchecked are likely to significantly contribute to escalation risks, including nuclear escalation risks, through multiple pathways. These pathways, discussed in greater detail in the following sections, include, inter alia, preemptive attack postures contributing to first-strike instability, national leadership targeting, and inadvertent escalation through misperceiving the intention behind missile strikes in times of war. Moreover, U.S. policymakers in particular must contend with a regional environment where treaty allies will be increasingly capable of delivering strategic effects on the battlefield with conventional missile capabilities, which could beget a nuclear response from China or North Korea under certain conditions.8 These dynamics demand sustained attention from U.S. and allied policymakers and military planners, who must explore and understand various escalation pathways and further coordinate their operational planning for various contingencies. Finally, the growing variety of missile capabilities could introduce technologically determined sources of escalation risk, including those pertaining to payload ambiguity,9 target ambiguity, and platform ambiguity. National defense establishments in the region have not sufficiently considered these risks as they have pursued missiles as an essential, cost-effective means of projecting power to various ends. To mitigate risks and avert spirals in future crises, policymakers and military planners must first recognize the array of risks and pathways to nuclear escalation that exist. Following this, defense policy processes and military plans can adapt to mitigate unnecessary escalation risks that may stem from existing postures, and regional diplomatic processes can explore negotiated restraint to the fullest extent possible. The trend toward missile proliferation in East Asia is unlikely to soon be reversed, but it is imperative that regional decisionmakers fully understand the scope of potential escalation risks and, out of an interest in averting nuclear war, work to limit these risks.
Conceptual Overview of Missiles
Prior to exploring the drivers of vertical and horizontal proliferation in missile arsenals in the Indo-Pacific, it is essential to first taxonomize and define various surface-attack missile types to understand not only their putative advantages and drawbacks but also how they might contribute to escalation risks in times of crisis or conflict.10 Taxonomizing missiles is far from straightforward in the twenty-first century; traditional distinctions between ballistic missiles and cruise missiles, for instance, are insufficient in describing the contemporary missile landscape. Though technologies such as hypersonic glide vehicles and terminally maneuverable reentry vehicles are not conceptually novel, their proliferation both in Asia and elsewhere means that laying out the distinctions between various missile types can be beneficial for understanding varied risks and their implications.11
Despite the proliferation of complex missile types outside of research and development settings today, it is helpful to identify the fundamental concepts that unify all missile types. These characteristics can be understood as the sine qua non of missiles. At their core, all missile types make use of a chemical rocket booster for propulsion to both accelerate and elevate their payloads, which are weaponized in some form. This use of a weaponized payload, for instance, sets apart ballistic missiles from space launch vehicles (SLVs), which make use of rocket boosters and carry nonweaponized payloads, although large ballistic missiles could be used for space launch and SLVs could be used to carry weapons. Generally speaking (but not in all cases), the physical characteristics of the missile’s booster, including its mass and fuel capacity, are strongly determinative of its range, which for rocket systems in particular varies with the mass of the payload. This payload-booster distinction explains why missiles are sometimes referred to as delivery systems; the object being delivered by the booster at range is the weaponized payload. The incorporation of some form of guidance system further distinguishes missiles from more rudimentary types of rocket-equipped munitions, such as unguided rocket artillery. There are various technologies used to improve guidance capabilities, ranging from the gyroscopic accelerometer systems used in the earliest missiles, like the German V2, to the considerably more advanced computationally assisted, multimodal guidance systems on modern cruise missiles. Most of the contemporary complexity in describing missile types stems from the variety of possibilities concerning payload types. These possibilities are discussed in greater detail later.
Finally, while examining a given missile can spotlight its range and payload capabilities, all missiles in the real world are best understood as part of a broader system. This includes not only the missile itself but also its launcher as well as command-and-control systems, targeting subsystems, and, in the case of certain land-based missiles, fueling and reloading support vehicles.12 Beyond the performance of the missile itself, other characteristics of a missile system can have substantial influence on its military effectiveness and desirability. Solid-propellant missiles, for instance, obviate the need for fueling support vehicles by virtue of having their propellant cast into their airframes during the manufacturing process. With some exceptions, liquid propellant missiles generally require fueling at some point prior to use, rendering them less responsive in a crisis in some cases and potentially more vulnerable to preemption given the more substantial signatures associated with any fueling activity in the field.13
The Basics of Missile Types
Ballistic missiles with ballistic payloads. Ballistic missiles with ballistic payloads are the oldest type of continuously deployed land-attack missiles and among the most widely proliferated land-attack missiles in the world, including in East Asia. They are also the simplest to understand. Essentially, these missiles make use of rocket boosters to accelerate and elevate a payload on a particular azimuth—or direction—that then relies primarily on gravitational force to descend to a target. Apart from gravity, the sole other physical phenomenon influencing the behavior of a payload as it approaches its target after the booster burns out is atmospheric drag upon reentry. Most modern ballistic missiles feature separating reentry vehicles (RVs), which detach from one or more booster stages. (As the term “reentry” implies, the booster separates from the RV outside of the earth’s atmosphere.) These missiles rely on their guidance systems being cued prior to launch and thus are suited for use against known, stationary targets. When launched to long ranges, ballistic payloads reenter the earth’s atmosphere at high speeds. Regardless of the sophistication of their payload type, all missiles launched on a ballistic trajectory are prompt, with RVs arriving at their targets minutes after separation from their boosters. For much of the early missile age, the term “missile” was largely synonymous with “ballistic missile”; this has changed over time as cruise missiles and ballistic missiles using more advanced payloads with aerodynamic and impulsive maneuvering capabilities proliferated. Ballistic payload examples include the North Korean Hwasong-5/6, Russian R-17/Scud-B, and Chinese DF-11.
Ballistic missiles with aerodynamically maneuvering payloads. As mentioned earlier, gravity and atmospheric drag are the two salient physical phenomena that act on missile RVs, influencing their behavior. More advanced missiles often incorporate control surfaces and other physical features that can take advantage of aerodynamic drag to various ends. At the simplest end of the aerodynamically maneuvering payload spectrum are maneuvering reentry vehicles (MaRVs). These payloads use control surfaces to adjust the final trajectory of a separating RV after exoatmospheric ballistic flight to improve their accuracy against a fixed or mobile target and defeat terminal missile defense interceptors. Examples include the North Korean KN21, U.S. Pershing II, and Chinese DF-15.
A second type of aerodynamically maneuvering payload is the unitary aeroballistic (or “quasi-ballistic”) missile. These missiles do not feature separating booster stages—hence, they are “unitary,” combining booster and payload in a single object—and do not necessarily exit the earth’s atmosphere. Instead, the entirety of the missile’s body behaves as an aerodynamic object; after the missile’s booster burns out, the remainder of its flight features unpowered aerodynamic maneuvers. Aeroballistic missiles can behave similarly to MaRVs in their final moments of flight but otherwise glide at high speeds to their targets. Examples include the South Korean Hyunmoo-4, North Korean KN23, U.S. Army Tactical Missile System (ATACMS), and Russian Iskander-M.
A final type of aerodynamically maneuvering payload is the hypersonic glide vehicle (HGV). HGVs are often regarded as a distinct type of hypersonic missile, but they behave according to the same physical principles as other payloads in this category and can be thought of as lying at the far end of a spectrum from MaRVs, which only maneuver in their terminal phase. Like MaRVs, HGV payloads incorporate physical design features to take advantage of aerodynamic lift and drag forces. Also like MaRVs, HGVs separate from booster stages. Unlike MaRVs, however, they reenter the earth’s atmosphere much sooner in their flight trajectories and spend the majority of their total flight time gliding at hypersonic speeds (defined as greater than five times the local speed of sound in a given medium14); in this way, they are also similar to aeroballistic missiles. These shared attributes explain why these three payload types are best understood as part of the same overall capability spectrum. Compared to purely ballistic missiles, however, HGVs can exhibit a longer time-to-target. While HGVs are capable of maneuvering throughout their flight, substantial maneuvers early in an HGV’s flight trajectory will come at the cost of speed and range.15 While the physical principles behind HGVs have been understood for decades,16 advances in materials science and guidance have allowed these systems to become practically deployable weapon systems. HGV payloads endure tremendous thermal and aerodynamic stresses in flight. Beyond this, growing concerns about area and point missile defenses have prompted interest in these capabilities within various military establishments around the world, including in Asia. Examples of HGVs include the Chinese DF-17, U.S. Dark Eagle, and North Korean Hwasong-8.
Ballistic missiles with powered maneuvering payloads. A third distinct category of ballistic payload features active propulsion, either on the RV itself or on a post-boost vehicle. The latter is most commonly associated with multiple independently targetable reentry vehicles (MIRVs) but can also be used to improve the accuracy of a single-RV payload. In the case of MIRVs, the powered “bus” payload carrying the RVs, once separated from its rocket booster stages outside the earth’s atmosphere, maneuvers to orient each warhead toward a distinct target and releases each warhead along its own ballistic trajectory to descend to its target relying primarily on gravitational force. The individual RVs may themselves exhibit other payload characteristics described above (such as terminal maneuvers). MIRVs are not a prominent feature of this report given their primary application in strategic intercontinental missile systems, but shorter-range MIRV capabilities are under development in South Asia by India and Pakistan and were deployed in Europe during the Cold War.
The second form of powered maneuvering payload—and the one more relevant to this report—comprises ballistic missiles designed to strike certain mobile targets, most prominently ships. This new type of missile is less understood in open sources, though it is often covered in news media given its novelty and potential to disrupt the prominence of sea power in the Indo-Pacific. Anti-ship ballistic missiles (ASBMs) likely require both exceptionally advanced RVs that incorporate features consistent with MaRVs and powerful kick motors to allow for rapid error-correction prior to and after reentry to strike mobile targets whose positions may change by hundreds of meters during the missile’s overall flight.17 ASBMs remain a niche capability, and their real-world performance remains uncertain. Examples include the Chinese DF-21D, Chinese DF-26 anti-ship variant, and Iranian Fattah missile.
Land-attack cruise missiles. Land-attack cruise missiles share little in common with the previously described missile and payload types. These missiles fly entirely within the earth’s atmosphere, exhibit powered flight with the use of sustainer propulsion throughout their whole trajectory, and are highly maneuverable. Contemporary long-range cruise missiles are “air-breathing,” meaning that they use the surrounding atmosphere as their oxidizer, increasing fuel efficiency. In many cases, cruise missiles will use a small chemical rocket booster to initiate their air-breathing sustainer engines.18 Their low-altitude flight, high maneuverability, and small size can in combination offer substantial advantages in stressing missile warning systems and defenses, which often detect cruise missiles only as they approach their targets. (Exoatmospheric ballistic missile payloads, by contrast, can be detected by surface radars at longer ranges due to their high altitudes.) While advanced cruise missiles, such as the U.S. Joint Air-to-Surface Standoff Missile (JASSM) and its variants, are considered low-observable munitions, even-more-rudimentary cruise missiles are challenging to track for most states. Traditionally, cruise missiles have been juxtaposed against ballistic missiles as the second major missile type, but the proliferation of nonballistic payloads described above suggests that this dichotomy is no longer appropriate. Most deployed cruise missiles feature turbofan or turbojet engines and fly at subsonic speeds; compared to the time-to-target of ballistic payloads, which are measured in minutes, cruise missiles are generally substantially slower. Advances in sustainer engines have allowed for some states to develop supersonic cruise missiles that incorporate ramjet and/or rocket engines. More advanced cruise missiles in development aspire to hypersonic speeds with the use of supersonic combustion ramjet, or scramjet, engines. These missiles still reach speeds in the relatively low end of hypersonic flight at Mach 5–8. Examples of subsonic cruise missiles include the U.S. Tomahawk, Chinese DF-100, South Korean Hyunmoo-3, and Taiwanese Hsiung Feng IIE; examples of supersonic cruise missiles include the Russian-Indian BrahMos and Chinese YJ-12; an example of a hypersonic cruise missile is the Russian Tsirkon.
Missiles in Modern Warfare
As explained earlier, missiles are, in essence, delivery systems for weaponized payloads at range. For this reason—and with the exception of strategic nuclear missiles designed to range across continents—theater-range missiles of all types are understood to have tactical and strategic effects comparable to those of traditional airpower, albeit with many qualitative advantages over crewed and uncrewed aircraft. Early theoretical examinations of the influence of missiles on modern war—especially in the nuclear age—took airpower theory as their starting point.19 The drivers of missile procurement and proliferation around the world today largely hew to these same principles. Missiles, like airpower and artillery, may not win wars on their own, but they are seen by military establishments and defense policymakers as critical enablers of victory. The difficulty of comprehensive missile defense or defeat—both as a practical matter and in terms of costs—also enhances the perceived deterrence potential of substantial missile arsenals. Deterrence-by-punishment strategies that rely on convincing an adversary of an assured ability to inflict damage are well served by large missile arsenals that cannot be easily or cost-effectively defended against, raising the perceived costs of aggression by an adversary. Many of these same characteristics render missiles the ideal delivery system for nuclear weapons; every nuclear-armed state today relies on missiles as its delivery system of choice, supplemented in some cases by other means of delivery.
Missiles, like airpower and artillery, may not win wars on their own, but they are seen by military establishments and defense policymakers as critical enablers of victory.
The most important qualitative improvement over the course of the missile age has been in precision guidance capabilities. Early missiles, lacking precision, were largely only seen as useful either for the delivery of massively damaging payloads, which could cause damage to their intended targets even if they strayed far off their notional aimpoints, or as weapons of terror against nonmilitary targets, such as cities. Lacking precision, a single missile or a small number of missiles could not be effectively used to achieve tactical effects on the battlefield, especially with conventional warheads. The advent of more precise missiles has significantly improved the value of missiles to modern militaries seeking to achieve tactical and strategic effects at long ranges and with conventional warheads. As this report demonstrates, states with significant conventional missile arsenals—or plans for them—in the Indo-Pacific aspire to use these capabilities to hold at risk a range of military targets to augment strategies of deterrence by denial and deterrence by punishment. Even missile pursuers that largely lacked precise missiles a little more than a decade ago, such as North Korea, have made substantial advances in precision guidance technologies.
The advent and proliferation of precision guidance have made missiles an attractive conventional military capability for many states, but even the most precise missiles depend on substantial enabling factors to prove effective in times of conflict. Robust intelligence, surveillance, and reconnaissance—both in peacetime and in times of conflict—is critical to assessing the location of mobile and fixed targets. Missiles themselves are the final link in the long-range strike kill chain, which depends, as it has for decades, on the ability to find, fix, and finish targets. As missiles proliferate for offensive use, defenders adapt. China and North Korea, for instance, have for many years feared U.S. long-range precision strike capabilities and thus exhibit a strong preference for road-mobile theater-range missile systems, hoping to complicate as much of the kill chain as possible and improve survivability. However, fixed targets, such as known command-and-control nodes and support facilities, remain especially vulnerable and are thus attractive targets for long-range strikes. Defenders, as a result, look to active and passive defenses. (Active defenses comprise missile defense technologies, while passive defenses encompass camouflage, concealment, deception, mobility, and hardening, inter alia.) These measure-countermeasure dynamics are currently at play in the Indo-Pacific and will remain so as missile capabilities continue to proliferate.
In Asia, amid rising geopolitical tensions and a growing assessment by several states that the risk of interstate war is growing, defense budgets have surged, and long-range strike capabilities are almost universally valued. While military planners and policymakers are drawn to missiles due to their many desirable characteristics in augmenting conventional deterrence, they must better understand the risks that accompany rapidly proliferating missile arsenals. Furthermore, regional states are drawn to long-range strike capabilities for differing reasons.
Notes
1 In general, short-range missiles are those with ranges between 300 kilometers and 1,000 kilometers, medium-range missiles are those with ranges between 1,000 kilometers and 3,000 kilometers, and intermediate-range missiles are those with ranges between 3,000 and 5,500 kilometers.
2 Jeffrey W. Hornung, “Is Japan’s Interest in Strike Capabilities a Good Idea?,” War on the Rocks, July 17, 2020, https://warontherocks.com/2020/07/is-japans-interest-in-strike-capabilities-a-good-idea.
3 Kayleigh Madjar, “Lawmakers Pass NT$236.96bn Special Defense Budget,” Taipei Times, January 12, 2022, https://www.taipeitimes.com/News/front/archives/2022/01/12/2003771197.
4 Kingston Reif, “U.S. Aims to Add INF-Range Missiles,” Arms Control Association, October 2020, https://www.armscontrol.org/act/2020-10/news/us-aims-add-inf-range-missiles.
5 Ken Moriyasu, “‘Geopolitical Powder Keg’ Asia Jacks Up Global Military Spending,” Nikkei Asia, August 25, 2022, https://asia.nikkei.com/Politics/International-relations/Indo-Pacific/Geopolitical-powder-keg-Asia-jacks-up-global-military-spending . Time series data on regional defense spending is available from the SIPRI Military Expenditure Database, Stockholm International Peace Research Institute, accessed September 2023, https://www.sipri.org/databases/milex.
6 “U.S. Collective Defense Arrangements,” U.S. Department of State, accessed October 18, 2022, https://2009-2017.state.gov/s/l/treaty/collectivedefense/index.html.
7 Nan Li, “60 Years On, China-North Korea Treaty Still Important for Cooperation and Peace,” NK News, July 11, 2021, https://www.nknews.org/2021/07/60-years-on-china-north-korea-treaty-still-important-for-cooperation-and-peace; and Seong-hyon Lee, “China-N. Korea Defense Treaty,” Korea Times, July 26, 2016, http://www.koreatimes.co.kr/www/opinion/2019/07/197_210355.html.
8 Tong Zhao, “Conventional Long-Range Strike Weapons of US Allies and China’s Concerns of Strategic Instability,” Nonproliferation Review 27, no. 1–3 (January 2, 2020): 109–122, https://doi.org/10.1080/10736700.2020.1795368.
9 James M. Acton, “Is It a Nuke?: Pre-launch Ambiguity and Inadvertent Escalation,” Carnegie Endowment for International Peace, April 9, 2020, https://carnegieendowment.org/2020/04/09/is-it-nuke-pre-launch-ambiguity-and-inadvertent-escalation-pub-81446.
10 This report largely excludes air-to-air, surface-to-air, and anti-ship missiles (with the exception of anti-ship ballistic missiles) because of their tactical roles.
11 Steven T. Dunham and Robert S. Wilson, “The Missile Threat: A Taxonomy for Moving Beyond Ballistic,” Aerospace Corporation, August 2020, https://csps.aerospace.org/sites/default/files/2021-08/Wilson-Dunham_MissileThreat_20200826_0.pdf.
12 Markus Schiller, “Missile Identification and Assessment,” International Institute for Strategic Studies, April 1, 2022, https://www.iiss.org/blogs/research-paper/2022/04/missile-identification-and-assessment.
13 This does not mean that solid-propellant missiles are without undesirable features. Difficulty in casting propellant grain for large missiles, for instance, along with long-term storage and handling difficulties, can make liquid-propellant systems somewhat more reliable for less-experienced missile powers.
14 Within the earth’s atmosphere, the local speed of sound varies primarily with temperature.
15 Cameron L. Tracy and David Wright, “Modelling the Performance of Hypersonic Boost-Glide Missiles,” Science & Global Security 28, no. 3 (2020): 135–170, https://scienceandglobalsecurity.org/archive/2020/12/modelling_the_performance.html.
16 James M. Acton, “Silver Bullet? Asking the Right Questions About Conventional Prompt Global Strike,” Carnegie Endowment for International Peace, September 3, 2013, https://carnegieendowment.org/2013/09/03/silver-bullet-asking-right-questions-about-conventional-prompt-global-strike-pub-52778.
17 Dunham and Wilson, “The Missile Threat: A Taxonomy for Moving Beyond Ballistic,” 15–16.
18 Air-launched cruise missiles may be able to forgo the use of a chemical rocket booster if they are released from an aircraft at sufficient speed to initiate the on-board sustainer engine. This is true of most air-launched cruise missiles in use today.
19 Bernard Brodie, “Strategy in the Missile Age,” RAND Corporation, October 8, 2007, https://www.rand.org/pubs/commercial_books/CB137-1.html.