The current U.S. framework for “deterrence in space” fails to incorporate the uniqueness of space relative to all other warfighting domains and the subsequent effect space has on asymmetric deterrence, particularly through the application of punishment logic. This deficiency is exacerbated by a lack of adequate care for the communication and credibility of U.S. asymmetric threats as a means to deter space attacks. The United States will fail to prevent the wide range of attacks that it hopes to deter in space and further convince its adversaries that it cannot adequately distinguish the stars from the constellations in space conflict without the addition of certain supplemental policies, such as publicly signaled escalation ladders.
The United States must operationalize deterrence in space because international actors, both friendly and adversarial, are developing their capabilities and will evolve into space powers.[i] Adversaries may exploit the United States’ vulnerability in space to degrade U.S. military capabilities, not just in and through space, but across all domains.[ii] To prevent this, the United States requires a credible strategy to deter attacks on space assets.
The United States’ framework for “deterrence in space” is a domain-specific extension of its overall strategic policy – integrated deterrence. However, the unaltered application of integrated deterrence’s asymmetric retaliation logic to space undermines the credibility and success of U.S. space deterrence due to three unique characteristics of military operations in space: (1) the exclusive deployment of unmanned military space assets; (2) the preponderance of dual-use space assets; and (3) the outsized lethality of non-kinetic capabilities in space.[iii]. These characteristics impede asymmetric deterrent threats from achieving the same success in space as in traditional warfighting domains (land, sea, and air). As such, the United States’ framework for space deterrence underestimates the difficulty of determining cross-domain equivalencies relative to space; fails to adequately deal with the diversity of space attacks; and neglects two of the three major “Cs” of deterrence, communication and credibility. Publicly declared escalation ladders contextualizing various space attacks with cross-domain equivalents can solve these issues and increase the credibility of U.S. deterrence in space.
Theories of “Deterrence in Space”
The concept of the “three Cs” (capability, communication, and credibility) is inherent to all theories of deterrence, no matter the domain or context.[iv] Capability refers to having the ability to either deny a rival offensive gains or impose sufficient punishment ex post facto.[v] Communication refers to demonstrating to a rival one’s intention to deter a specific action in a way that they understand.[vi] Credibility refers to the believability of one’s capacity to deny an opponent offensive gains and the believability of threatened retaliation.[vii]
Theoretical concepts of deterrence in space usually draw from two distinct, yet intertwined perspectives: deterrence by denial and deterrence by punishment.[viii]Deterrence by denial, sometimes referred to as deterrence by resilience, focuses on convincing an opponent that the probability of successfully taking an offensive action is so low that it is not worth pursuing in the first place.[ix] States can accomplish this in the space domain by taking risk distribution actions like fielding satellites that are resilient to multiple attacks and by increasing redundant capabilities.[x]Alternatively, deterrence by punishment focuses on convincing opponents that the value of an offensive action, even if successful, will not outweigh the cost of the response.[xi] In space, states can achieve this in several ways including by developing cyber, electronic, or kinetic space weapons to demonstrate their ability to inflict harm.[xii]
The United States layers these two perspectives to create one unified theory for space.[xiii]This theory first emphasizes deploying resilient space systems with high rates of survivability against various attacks.[xiv] Then it calls for the United States to retaliate proportionately against the identified attacker.[xv] Thus, the United States intends to use denial as a first line of defense, hoping to dissuade attacks by increasing the difficulty of their success.[xvi] If that fails, its framework reverts to conceptions of punishment whereby the United States will retaliate against attackers to inflict proportionate harm.[xvii]
This space deterrence framework warns that retaliatory actions by the United States are liable to be asymmetric, meaning that they will occur in a different domain from the original attack if need be.[xviii] It asserts that the United States will retaliate to attacks on its space assets “at a time, place, manner, and domain of [its] choosing.”[xix]This policy reflects the United States’ asymmetric threat environment. As the preeminent space power, the United States is vulnerable to attacks in space due to its dependence on satellites for almost all of its military communication, targeting, and nuclear command and control abilities.[xx]Therefore, the United States must threaten to employ deterrence by punishment related to space asymmetrically to impose equivalent costs because U.S. adversaries are not as dependent on space assets – thus not as vulnerable – when it comes to employing their national security and military forces. [xxi]
U.S. reliance on asymmetric deterrents is rooted in the 2022 U.S. National Security Strategy and the 2022 National Defense Strategy. [xxii]These strategies rely on a concept of “integrated deterrence” as a means of deterring all possible offensive rival actions in all domains by “working seamlessly across warfighting domains, theaters, the spectrum of conflict, all instruments of U.S. national power, and [its] network of Alliances and partnerships.”[xxiii] These strategies, in essence, warn potential adversaries that the United States is liable to respond asymmetrically, not just to an attack in space, but to an offensive action in any domain.[xxiv] In this way, the United States’ space deterrence policy acts as a domain-specific extension of its overall strategic posture.
The Uniqueness of Space and Problems with Asymmetric Deterrents
The unaltered adoption of integrated deterrence’s asymmetric retaliation logic may seem sufficient for discouraging attacks on American space assets. In practice, however, it undermines the United States’ ability to deter space attacks due to three unique characteristics of military operations in space. First, unlike in traditional warfighting domains, all modern military space assets are unmanned.[xxv] Second, many satellites serve dual-use missions (simultaneous civilian and military missions).[xxvi] Third, non-kinetic capabilities, which often include weapons whose existence, potential threat, or actual use is not easily perceived by other states, are particularly lethal to satellites relative to military assets in other domains.[xxvii] Non-kinetic capabilities include electronic, cyber, and non-kinetic physical weapons.[xxviii]These features impede the credibility of the United States’ “at a time, place, manner, and domain of our choosing” deterrence logic relative to space in ways not experienced by integrated deterrence’s asymmetric threats in traditional warfighting domains.[xxix]
During the Cold War, the United States and Soviet Union developed a shared perception of the stages of armed conflict. This shared perception included actions that constituted escalations in both severity and scope.[xxx] Both the United States and Soviet Union recognized that the use of chemical and biological weapons constituted an escalation in kind above conventional conflict, but right below nuclear war.[xxxi]Similar shared perceptions about escalation thresholds within conventional conflict such as broadening the geographic locale or raising the intensity of violence ensured that each state could respond in kind to an attack or crisis largely without the risk of escalation to a more destructive, unintended level.[xxxii]These shared perceptions allowed each state to construct deterrent threats that seemed neither escalatory nor insufficiently forceful for each type of action they intended to deter.[xxxiii]Thus, deterrent threats, symmetric and asymmetric alike, maintained their credibility and therefore their effectiveness. However, determining credible, equivalent, and non-escalatory responses to space attacks across domains is more complex than the U.S. framework assumes because of the lack of consensus about space and space’s unique characteristics.[xxxiv]
A salient issue that deterrence postures must contend with is the lack of manned, military space assets. Threatening to retaliate in non-space domains where human casualties are probable in response to attacks on space assets might seem like unwarranted escalation to U.S. adversaries and thus not credible.[xxxv]China likely perceives counterspace attacks as less provocative and escalatory than terrestrial ones precisely for the absence of human casualties.[xxxvi]This interpretation is unlikely to be shared in Washington to the same degree due to the United States' dependence on satellites for its most critical national security functions, including command and control of its nuclear arsenal.[xxxvii]The credibility of asymmetric space deterrents suffers when the diversity of space-attacks is considered. The four main types of space attacks are kinetic physical, non-kinetic physical, electronic, and cyber.[xxxviii] Each of these categories represents numerous specific attacks, which can be either reversible or irreversible.[xxxix]While it might be reasonable to assume that American threats to respond kinetically in a non-space domain to an electronic or cyber-attack in space are sufficiently escalatory to lack credibility, other potential scenarios are complex.
One such scenario includes the Chinese use of a kinetic anti-satellite (ASAT) weapon.[xl]Under such a scenario, the United States might understand its ambiguous “at a time, place, manner, and domain of our choosing” deterrence logic to mean that it will retaliate using kinetic weapons in a non-space domain. [xli]From the U.S. perspective, a kinetic response would be warranted given the preceding use of a kinetic ASAT weapon by the Chinese.[xlii]The American perspective is also likely to assume, given the asymmetric nature of its threats and the relatively smaller military importance of Chinese satellites, that the Chinese understand that American retaliation is likely to occur in a non-space domain where the United States perceives a target of equivalent value to exist.[xliii]Given Chinese perceptions that attacks in manned domains are escalatory relative to those in unmanned domains, China might understand American asymmetric deterrent threats to mean that in response to a kinetic ASAT attack the United States might initiate a cyber-attack, for instance, across domains, preserving China’s non-lethality principle.[xliv]Risking casualties by responding kinetically in a non-space domain might seem escalatory to the Chinese and thus not a credible American deterrent.[xlv] The ambiguous threats used by the United States leave room for various interpretations about what is proportional, hindering the effectiveness of their deterrent properties because effective deterrence relies on shared perceptions of equivalence and credibility between adversaries.[xlvi] U.S. adversaries will not find America’s asymmetric response doctrine credible nor be deterred from taking offensive space actions where they do not perceive equivalence between non-lethal space attacks and lethal attacks in non-space domains.[xlvii]
Similar questions about escalation arise regarding U.S. responses to attacks on dual-use satellites. The United States’ asymmetric vulnerability in space means that U.S. space assets are enticing targets for adversaries.[xlviii]However, these adversaries possess less technologically advanced, blunt force anti-space weapons that might not be capable of targeting the specific militarized parts of satellites.[xlix]Therefore, an adversary might be forced to attack an entire satellite to take out a U.S. military space capability, destroying both military and civilian capabilities.[l]American adversaries with such limited anti-space capabilities will likely have insufficient space assets to make retaliation in space a viable deterrent threat, forcing the United States to respond asymmetrically.
Such a situation poses serious questions about what adversarial perceptions of non-escalatory responses across domains might look like. Is the United States justified in responding disproportionately against military targets in non-space domains to make up for the damage caused to its civilian space systems without escalating the conflict? Will the adversary perceive the answer to this question in the same way as the United States? Or will adversaries assume that non-escalatory retaliation entails damage equivalent only to that originally caused to military systems?
Recent events have demonstrated that differences in perception between the United States and its adversaries about attacks on dual-use satellites are not merely theoretical, but realities.[li]In late 2022, after a Russian official declared that U.S. commercial satellites assisting the Ukrainian war effort could become legal military targets, many U.S. officials and academics argued the opposite, citing the ambiguity of international laws and the lack of precedent.[lii] While the ensuing discussion revolved around the legality of an initial attack and not around the credibility of a retaliatory deterrent, this episode highlights the lack of consensus about the escalatory nature or lack thereof of attacks on dual-use satellites or their corresponding retaliation.[liii]The United States’ ambiguous asymmetric deterrent threats (and outcomes) fail to deal with such potential cases. This ambiguity damages credibility by leaving room for different plausible expectations of American retaliatory actions.[liv] It is hard to deter by denial or punishment if an adversary does not view the cost-benefit calculation of offensive action in a similar fashion to the deterrer.[lv]
The lethality of non-kinetic capabilities in space ensures that the United States’ space deterrence posture once again fails to address the expansive range of space attacks. No one concept or threat can deter numerous incomparable types of attack within one domain, in particular not one that fails to specify the types of retaliatory actions it would take for each kind of attack. No adversary will consider the United States’ deterrent threats credible if it does not differentiate between type and severity of attack.[lvi] It is not credible to assert that a reversible cyber-attack will garner the same retaliatory response as blowing up an American satellite.[lvii] This is especially true given that the majority of space attacks are non-kinetic in nature.[lviii] The possible imperceptibility of non-kinetic attacks themselves (such as whether a satellite collision was accidental or intentional) or of their malicious intent by victims and third-parties (such as whether jamming or spoofing is the product of an attack or unintentional interference) complicates the credibility of asymmetric deterrent threats.[lix] It is not credible to assert that a non-kinetic attack which is imperceptible to the international community will garner the same retaliatory response as an attack easily observed by third-parties.[lx]
Given the United States’ lack of publicly stated red lines or ladders of escalation for space, adversaries are likely to try their luck with non-kinetic attacks, increasing the severity to test American willingness to respond.[lxi]This process, called “salami tactics,” is itself a failure of deterrence since it fails to stop an adversary from acting in the first place.[lxii]The lack of clear, specific, and credible deterrent threats for each type of attack incentivizes adversarial probing, which has emboldened both China and Russia to perpetrate daily non-kinetic probing attacks on American space assets.[lxiii] Sustained, unrequited probing will degrade space assets and may result in adversaries unknowingly breaching undeclared redlines.[lxiv] In the face of the unique characteristics of space, the credibility of American deterrence in space is hindered by its unaltered adoption of integrated deterrence’s asymmetric retaliation logic.
These complications and challenges would not be so damaging if the United States attended to the other two “Cs” of deterrence, communication and credibility. Under the current framework, the conversation and literature revolve around how to harden assets, how to increase survivability, and which new space systems to field.[lxv]Less discussed is how to communicate the existence, effectiveness, and lethality of these new capabilities to American adversaries.[lxvi] Concerns about whether U.S. deterrence posture in space is considered sufficiently credible to prevent adversarial actions are also neglected.[lxvii]
This neglect is a problem not because novel space capabilities are not needed to combat the peculiarities of space, but because the other two Cs of deterrence, communication, and credibility, deserve equal attention. As already discussed, the unique characteristics of space hamper the credibility of asymmetric deterrent threats in ways not experienced in traditional warfighting domains. Along with these challenges, the United States does not adequately specify equivalent retaliatory actions across domains, communicate why they are not escalatory, or give credence to their credibility.[lxviii] Considering the lack of known precedent in responding militarily in a non-space domain to an attack in space, convincing an adversary of one’s own beliefs about equivalence and escalation requires additional effort.[lxix] While decades of previous U.S. actions and policies bolster the credibility of asymmetric deterrence in traditional warfighting domains, most of these signals are not relevant or transferable to deterrence in space. The lack of adequate attention to communication and credibility demonstrates a failure to attend to the uniqueness of space, thus damaging U.S. deterrence efforts in space.
Fixing Deterrence in Space
The challenges posed by the unique characteristics of space on U.S. deterrence primarily affect the credibility of its secondary deterrence by punishment logic. The United States can ameliorate this problem by increasing communication with declared space escalation ladders, which will bolster credibility.[lxx]
The United States has some leeway on how it constructs its escalation ladders, but it must consider some key factors. Escalation ladders must rank, to some degree, the severity of the different types of attacks in space and perceptions of non-escalatory retaliation.[lxxi]This can be done by prioritizing attacks by their type, reversibility, or both. Given the United States’ asymmetric punishment logic, any American escalation ladder should contextualize specific types of space attacks within a holistic view of attacks and escalation in all domains.
However, how the United States constructs its escalation ladders is less important than the fact that it declares them publicly as conceptual frames of reference.[lxxii] Such communication will not only aid American policymakers and strategists in determining asymmetric deterrents suitable for the uniqueness of space but will also increase their credibility by providing adversaries with reference points for understanding how offensive space actions might be perceived by the United States.[lxxiii]In contrast to other areas where ambiguity enhances the effectiveness of U.S. deterrence, the uniqueness of space necessitates some clarity.[lxxiv] The complete lack of precedent for asymmetric punishment in response to space attacks and the non-transferable nature of previous U.S. behavior to space means that without a public escalation ladder, adversaries have no reference points with which to evaluate American credibility in space. When it comes to space, a continued overabundance of ambiguity will undermine the credibility of deterrence to a greater degree than disadvantages associated with publicly declared escalation ladders. Thus, public escalation ladders will improve the credibility of deterrent threats in response to attacks in space by minimizing ambiguity and potential misperceptions caused by the peculiarities of the domain.[lxxv]
Escalation ladders can be inserted into military doctrines, publications, speeches, and other official communications. Effective communication may take other forms, such as incorporating American perceptions of cross-domain equivalence into space-related military exercises. With this small but necessary fix, the asymmetric punishment logic of U.S. space deterrence posture can be remedied and appropriately adapted to reflect the needs of space.
The United States’ framework for “deterrence in space” fails to address three unique characteristics of military operations in space: the exclusive deployment of unmanned military space assets; the preponderance of dual-use space assets, and the outsized lethality of non-kinetic capabilities in space. This failure impedes the United States’ ability to operationalize its asymmetric punishment logic in space to the extent it does across traditional warfighting domains. America’s framework underestimates the difficulty of determining cross-domain equivalencies relative to space; fails to deal with the diversity of space attacks; and neglects two of the three major “Cs” of deterrence, communication and credibility. The United States can fix its space deterrence posture by communicating its perceptions of equivalency and escalation to its rivals. Using publicized and specific escalation ladders that contextualize space attacks within the broader scope of conflict, the United States can credibly deter its rivals from offensive actions in space. Without such signals, it is likely that the United States will fail to prevent the offensive space actions it intends to deter.
Timothy Georgetti is a M.A. candidate in the Security Studies Program in the Walsh School of Foreign Service at Georgetown University. He has particular expertise in the areas of U.S. national security policy and emerging technologies. This paper solely represents the author's views and does not necessarily represent the official policy or position of any Department or Agency of the U.S. Government. If you have a different perspective, we’d love to hear from you.
[i] Kari A. Bingen, Kaitlyn Johnson, and Makena Young, “Space Threat Assessment 2023,” (Center for Strategic and International Studies (CSIS), April 2023).
[ii] Roger G. Harrison, Deron R. Jackson, and Collins G. Shackleford, “Space Deterrence: The Delicate Balance of Risk,” Space and Defense 3, no. 1 (Summer 2009).
[iii] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice” (Harvard University, 2023); In this context, asymmetric deterrents, are those that threaten to respond to an initial attack in a different warfighting domain. Threatening to respond to an attack in space with an attack on land would be an example of an asymmetric deterrent.
[iv] Bryan Boyce, “21st Century Deterrence in the Space War-Fighting Domain: Not Your Father’s Century, Deterrence, or Domain,” Air & Space Power Journal, Spring 2019.
[viii] John J. Klein, “Chapter 4: Space Deterrence and the Law of War,” in Understanding Space Strategy: The Art of War in Space, 1st ed. (New York, New York: Routledge, 2019).
[ix] Todd Harrison et al., “Space Deterrence and Escalation,” Escalation and Deterrence (Center for Strategic and International Studies (CSIS), 2017); Department of Defense, “National Defense Strategy of the United States of America” (Washington, D.C.: Department of Defense, 2022).
[x] John J. Klein, “Chapter 4: Space Deterrence and the Law of War;” Michael Traut and Christoph Muller, “Deterrence in the Space Domain,” Joint Air & Space Power Conference 2022 Read Ahead (Joint Air Power Competence Center (JAPCC), June 2022).
[xi] Todd Harrison et al., “Space Deterrence and Escalation.”
[xiii] Christopher M. Stone, “Deterrence in Space: Requirements for Credibility,” RealClear Defense, December 1, 2020; Dean Cheng and John J. Klein, “A Comprehensive Approach to Space Deterrence,” The Strategy Bridge, March 31, 2021; Department of Defense, “National Defense Strategy of the United States of America” 8-11.
[xviii] Rafał Kopeć, “Space Deterrence: In Search of a ‘Magical Formula,’” Space Policy 47 (2019): 124.
[xix] Christopher M. Stone, “Deterrence in Space: Requirements for Credibility.”
[xx] Roger G. Harrison, Deron R. Jackson, and Collins G. Shackleford, “Space Deterrence: The Delicate Balance of Risk;” Rafał Kopeć, “Space Deterrence: In Search of a ‘Magical Formula,’” 124.
[xxii] White House, “National Security Strategy of the United States of America” (Washington, D.C.: White House, October 2022); Department of Defense, “National Defense Strategy of the United States of America.”
[xxiii] White House, “National Security Strategy of the United States of America;” Department of Defense, “National Defense Strategy of the United States of America, 1.”
[xxv] John J. Klein, “Chapter 4: Space Deterrence and the Law of War.”
[xxvii] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice.”
[xxix] Christopher M. Stone, “Deterrence in Space: Requirements for Credibility.”
[xxx] Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”, NDU Strategic Forum, no. 272 (December 2011).
[xxxiv] Department of Defense, “National Defense Strategy of the United States of America,” 6; Department of Defense, “2022 Nuclear Posture Review” (Washington, D.C.: Department of Defense, 2022), 6.
[xxxv] Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”.
[xxxvi] Scott Pace, “A U.S. Perspective on Deterrence and Geopolitics in Space,” Space Policy, July 2023.
[xxxvii] Todd Harrison et al., “Space Deterrence and Escalation,” 33.
[xxxviii] Kari A. Bingen, Kaitlyn Johnson, and Makena Young, “Space Threat Assessment 2023.”
[xl] Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”.
[xli] Christopher M. Stone, “Deterrence in Space: Requirements for Credibility;” Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”
[xliv] Ibid.; Scott Pace, “A U.S. Perspective on Deterrence and Geopolitics in Space.”
[xlv] Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”.
[xlvi] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice,” 30-36.
[xlvii] Rafał Kopeć, “Space Deterrence: In Search of a ‘Magical Formula,’” 121-129.
[xlviii] Roger G. Harrison, Deron R. Jackson, and Collins G. Shackleford, “Space Deterrence: The Delicate Balance of Risk.”
[li] Joey Roulette, “Russia’s Anti-Satellite Threat Tests Laws of War in Space,” Reuters, October 28, 2022, sec. World; Reuters, “Russia Warns West: We Can Target Your Commercial Satellites,” Reuters, October 21, 2022, sec. World; Jon Brodkin, “Russian Official Says Civilian Satellites May Be ‘Legitimate’ Military Target,” Ars Technica, September 16, 2022; Eric Berger, “Russia Threatens a Retaliatory Strike against US Commercial Satellites,” Ars Technica, October 27, 2022.
[liv] Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”; Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice,” 30-40; Scott Pace, “A U.S. Perspective on Deterrence and Geopolitics in Space.”
[lv] Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”
[lvi] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice,” 54-58
[lvii] Todd Harrison et al., “Space Deterrence and Escalation.”
[lviii] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice.”
[lxi] Thomas Schelling, Arms and Influence, Veritas Paperback (United States of America: Yale University Press, 2020).
[lxiii] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice,” 44-45.
[lxiv] Ibid.; Thomas Schelling, Arms and Influence.
[lxv] Christopher M. Stone, “Deterrence in Space: Requirements for Credibility;” Todd Harrison et al., “Space Deterrence and Escalation;” Dean Cheng and John J. Klein, “A Comprehensive Approach to Space Deterrence;” Michael Traut and Christoph Muller, “Deterrence in the Space Domain;” Department of Defense, “National Defense Strategy of the United States of America;” White House, “National Security Strategy of the United States of America.”
[lxix] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice,” 29-30.
[lxx] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice.”
[lxxi] Rafał Kopeć, “Space Deterrence: In Search of a ‘Magical Formula.’”
[lxxii] Vincent Manzo, “Deterrence and Escalation in Cross-Domain Operations: Where Do Space and Cyber Fit?”
[lxxiv] Kaili Ayers, “Emerging Anti-satellite Capabilities and the Recourse to Deterrence Theory in Practice.”
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