【知远导读】本文为美国国会研究服务局为国会提供的关于关岛基础设施和战备问题的分析报告——《关岛：国防基础设施和战备》。该报告分析了关岛在美国国防事务中的重要作用，对关岛现驻兵力、军事基础设施、防空和导弹防御系统以及民用基础设施的现状进行了说明，阐明加强关岛基础设施建设对增强美军西太平洋军事准入能力的重大意义，并就关岛的防御问题、基础设施建设问题向国会提出了建议。

报告原文约2.5万字，篇幅所限，推送部分为节选。

关岛是美国在太平洋上最西端的领土，位于夏威夷以西6100多千米处。该岛长约48千米，是美国的一处“未合并领土”。¹美国众议院内设有无投票权的关岛代表。美国军队拥有岛上约25%的土地，并维持着一支约有6400名现役军人的部队（表1）。²关于关岛在美国国家安全战略中的重要地位，一些高级军事领导人都有过反复强调。³自2011年以来，美国军方提高了对太平洋地区的关注度，部分表现于增加关岛的基础设施建设投资和前沿部署资产。⁴在地理位置上，关岛离北京比夏威夷更近，这一特点使得该岛在支持美国在太平洋地区的海军和空军行动方面发挥着重要作用。⁵美国印太司令部领导人认为，关岛对支持美军在该地区的存在、威慑和力量投射等战略事务方面极其重要。2022年5月，美国印太司令部司令约翰·阿奎利诺（John C. Aquilino）海军上将指出，“关岛的战略重要性怎么强调都不过分。”⁶

表1.美国防部驻关岛人员

同时，美国国防部高级官员也曾经指出，由于地理位置的特殊性和战略价值的重要性，关岛也是一个极易受到攻击的打击目标。⁷关岛位于中国和朝鲜弹道导弹和核能力导弹的打击范围之内，包括中国人民解放军的某型DF弹道导弹（一些中国媒体报道称之为“关岛杀手”）。⁸为了保护关岛免受导弹袭击，美国导弹防御局（MDA）正在岛上开发、建设一个防空和导弹防御系统。该局官员表示，新导弹防御系统的某些组件可能会在2024财年末投入使用。⁹

一些分析人士认为，关岛的有效防御对于阻止中国大陆对台湾地区采取军事行动至关重要。¹⁰一位分析人士将关岛描述为“美国不可或缺的战略枢纽”，“使美国能够成功地在印太地区投射力量，从而向位于那里的主要美国盟友做出可信的安全承诺。”¹¹虽然美国在日本和韩国驻有数千名军人，但是如果台湾地区有事，日本和韩国政府是否会为美国的进攻性军事行动提供充分的合作和支持，仍然是一个无法得到确切答案的疑问。¹²在发生地区冲突时，为了达到延缓或者限制美军在西太平洋行动能力的目的，中国军队可能会把关岛作为他们的一个打击目标。¹³

中国和朝鲜都拥有能够打击关岛的核武器和导弹。部分观察家评估认为，关岛在攻击面前是比较脆弱的，因为其针对弹道导弹、巡航导弹或者高超声速导弹的防御手段较为薄弱。¹⁴美国导弹防御局运营总监米歇尔•阿特金森(Michelle Atkinson)在2023年3月发言指出：“目前的部队有能力保卫关岛免受当前朝鲜弹道导弹的威胁。然而，关岛面对的区域性挑战，同样会来自中国方向，且仍在迅速加剧。”¹⁵

目前，美国军队部署于关岛的导弹防御实力主要是“萨德”反导弹防御系统。¹⁶陆军驻关岛“萨德”反导连包括约100名官兵，装备有6个八联装拦截弹发射架。¹⁷美国海军根据需要为关岛提供额外的导弹防御能力，主要方式是在该地区部署配备了“宙斯盾”导弹防御系统的军舰，主要职能是拦截处于飞行中段或末段的导弹。¹⁸“萨德”系统和“宙斯盾”系统目前尚未集成，而是依赖于各自独立的传感器和指挥控制系统运行。

2022年10月，美国导弹防御局称，印太司令部发布了关于升级改造关岛导弹防御系统的新需求，包括“对区域弹道导弹、机动弹道导弹、高超声速滑翔器和巡航导弹等威胁的360度全覆盖分层式防御。”¹⁹

开发和运用导弹防御系统以保护关岛的军人、基础设施和美国居民免受潜在攻击，是印太司令部和导弹防御局领导层的顶层优先级任务。²⁰印太司令部指挥官在听证会上陈述指出，“关岛导弹防御系统仍然是印太地区的头号优先事项。这是基于最重要的国土防御任务而得出的结论。”²¹

《2022年导弹防御评估》高度强调了关岛的重要性：

“在国土防御的范畴内，任何对手对关岛或任何其他美国领土的攻击都将被视为对美国的直接攻击，并将得到适当的回应。此外，关岛是关键地区力量投射平台和后勤节点的根据地，也是美国努力维持自由和开放的印太地区的重要行动基地。因此，防御关岛这一美国领土免受导弹袭击的架构，将与其作为美国明确组成部分和重要地区位置的独特地位相称。关岛的防御将包括各种主动和被动导弹实力，将有助于一体化威慑的整体完整性，并加强美国在印太地区的作战战略。”²²

关岛加强版一体化防空和导弹防御系统

根据美国导弹防御局预算文件的表述，针对关岛的新型导弹防御架构，将于2024年具备“初始能力”，于2029年形成“增强能力”，并在2030年代继续发展。²³

该新系统将通过导弹防御局和三个军事部门的合作，把美国陆军的“萨德”导弹系统、美国陆军的“爱国者”（PATRIOT）导弹防御系统、美国海军的“宙斯盾”武器系统和美国海军的“标准-3”（SM-6）、“标准-6”（SM-6）导弹系统的诸项相关要素结合为一体，从而创造出一个全新的导弹防御系统。²⁴该系统将整合使用海军“宙斯盾”武器系统的火控能力和陆军的综合战斗指挥系统（IBCS），后者是能够把战场上的传感器和攻击器连结起来的指挥控制系统。²⁵导弹防御局官员称，该系统将包括分布式MK-41型垂直发射系统、陆军“标准”系列导弹发射架和一座AN/TPY-6型(前AN/TPY-X型)机动式四面相控阵雷达。²⁶关岛的导弹防御系统将由一个联合指挥中心通过综合战斗指挥系统、关岛“宙斯盾”系统和“指挥、控制、战斗管理与通信”(C2BMC)系统进行控制，以任务节点保障作战行动的本地连贯性。²⁷这些系统部分依赖于美国太空部队所维护的卫星和天基传感器网络。²⁸

美国参议院军事委员会2022年指出，关岛导弹防御计划“包括在全岛多个地点上对三个军种相关导弹防御计划的采购和系统整合工作，以应对由关岛有限的基础设施导致的一系列复杂的导弹相关威胁。”²⁹

2022年7月，导弹防御局发布了“意向通知”，表示最早将于2024年提供安装“宙斯盾关岛系统”的独家供货合同。³⁰

2023年5月5日，导弹防御局在《联邦公报》上发布了一份意向通知，要准备一份环境影响报告（EIS），以评估与用于关岛防御的加强版一体化防空和导弹防御系统相关的潜在环境影响以及所需要采取的缓解措施。³¹环境影响报告将评估分布于岛上的20个用于雷达、传感器、导弹发射架、导弹拦截器以及指挥、控制、战斗管理与通信系统的地面站点。³²

美国导弹防御局现任局长乔恩·希尔（Jon Hill）海军中将在2023年4月18日的听证会上对众议院武装力量委员会陈述表示：

“通过与各军种、机构合作，我们正在努力满足印太司令部对于持续性360度全覆盖层式防御的需求，即在关岛同时对抗巡航导弹、弹道导弹、机动式和高超声速威胁的能力。³³我们现在的全部重点都是建立站点。我们知道这些站点意味着什么。我们已经在那里完成了早期的环境性工作。正如你们提到的，在2024年底，我们的目标是建成第一座雷达、一个工程版本的指挥和控制包，以及一个发射架系统，这样我们就可以在环境中测试除了信号和检查之类的事务。因此，我们将在2024年底在岛上形成能力。”³⁴

关岛导弹防御计划的预期时间线

关岛导弹防御计划的监管

在《2023财年国防部拨款法》（P.L.117-328）中，美国国会指示导弹防御局每季度向国会国防委员会提供关岛导弹防御计划进展状态的最新报告。³⁵在《2023财年詹姆斯·因霍夫国防授权法案》（NDAA）（P.L.117-263）中，国会指示国防部与联邦政府资助的研发中心签订合同，对拟议的架构能力以及关岛导弹防御项目所需的军事人员和基础设施进行独立评估。³⁶《2023财年詹姆斯·因霍夫国防授权法案》还指示国防部任命一名高级军事官员，对用于关岛导弹防御系统架构设计的协调工作进行监督；监管为关岛导弹防御制定的一体化导弹防御采购战略的开发工作；确保军事部门和防务机构的预算适合该战略；部署一体化导弹防御系统；监管长期性采购和维护工作。³⁷该法案还要求，国防部长要设定好目标，要在“不迟于2023年12月31日”的时间表内“快速采购和部署3个垂直发射系统，这些系统要能够容纳计划中的海军拦截器。”³⁸

表2. 美国导弹防御局关岛防御计划预算（单位：百万美元）

资料来源：美国国防部、导弹防御局相关预算报告。

导弹防御系统的效能

科学家和防务专家围绕美国导弹防御技术展开了讨论。³⁹导弹防御局报告显示，导弹防御系统测试的成功率为82%。⁴⁰但是，一些政府审查人员和外部分析人士却对美国导弹防御局测试计划的数量和质量提出了质疑。⁴¹一些分析人士推测，如果发生军事冲突，中国军队可能能够实现至少25%的导弹防御渗透率。⁴²在《美国导弹防御评估》年度报告中，国防部表示美国的国家安全战略并不依赖导弹防御系统作为应对俄罗斯和中国导弹的主要手段；相反，美国“将继续依靠以安全、可靠和有效的核武器库为基础的战略威慑，应对和遏制来自中国和俄罗斯的、对美国本土的大型洲际核能力导弹挑战。”⁴³

在真实世界的军事冲突中，导弹防御的效能将依据大量各种因素而定。例如，对手部署大量导弹并同时发射多枚导弹的能力，就能够提高对导弹防御系统的渗透可能性。⁴⁴来袭导弹的类型及其支持技术也能够提高或者降低其规避防御措施的能力。⁴⁵另外，如果一个导弹防御系统能够向一枚来袭导弹发射数枚拦截弹，那么成功防御的可能性也会得到提高。⁴⁶根据国会预算办公室（CBO） 2021 年关于美国用于对抗对地攻击巡航导弹 （LACM） 的导弹防御系统的报告，当前导弹防御系统架构的可用拦截导弹数量有限，可能成为无法全面防御能发射大量导弹的对手攻击的一个因素。⁴⁷国会预算办公室指出，他们的分析是基于当前导弹防御架构而开展的。报告总结指出，“非国家群体以外的对手可能会获得更多的导弹，实力可能会超过国会预算办公室所标称的防御系统。”⁴⁸美国可能会考虑投资发展更多的拦截导弹能力。在这方面，国会预算办公室指出：

“决策者需要考虑广域巡航导弹防御的成本是否与对地攻击巡航导弹所带来的整体风险相匹配的问题。”⁴⁹

美国白宫发布的《2022年导弹防御评估》也是《美国国防战略》的一部分，其指出：“自50多年前美国开始开发第一个弹道导弹防御系统以来，进攻性空中和导弹威胁的发展速度已经大大加快。这一趋势代表着在未来十年里，日益增长的安全挑战在范围和复杂性方面都将倍数增长。”⁵⁰

【1】The Guam Organic Act of 1950 conferred U.S. citizenship on Guamanians, codified in Title 48, Sec. 1421 et seq of the U.S. Code.

【2】Defense Manpower Data Center, DOD Personnel, Workforce Reports & Publications, Military and Civilian Personnel by Service/Agency by State/Country, September 2022 and March 2023, at https://dwp.dmdc.osd.mil/dwp/app/dod- data-reports/workforce-reports. Also see Defense of Department, Military One Source, “Joint Region Marianas – Naval Base Guam In-depth Overview,” at https://installations.militaryonesource.mil/in-depth-overview/joint-region-marianas- naval-base-guam.

【3】For example, see Statement of Adm. John C. Aquilino, U.S. Navy Commander, U.S. Indo-Pacific Command, before the House Committee on Appropriations Subcommittee on Defense, U.S. Indo-Pacific Command Posture, May 17, 2022, p. 13, at https://docs.house.gov/meetings/AP/AP02/20220517/114752/HHRG-117-AP02-Wstate-AquilinoJ- 20220517.pdf. Also see 2022 National Defense Strategy, Missile Defense Review, which states: “Guam is home to key regional power projection platforms and logistical nodes, and is an essential operating base for U.S. efforts to maintain a free and open Indo-Pacific region.”

【4】See Oriana Skylar Mastro, “Defense, Deterrence, and the Role of Guam,” in Defending Guam, Ed. Rebeccah Heinrichs, Hudson Institute, July 2022), p. 44, at https://fsi-live.s3.us-west-1.amazonaws.com/s3fs-public/ defendingguamjuly2022.pdf; and Kimberly Underwood, “The Growing Importance of Guam,” Signal Magazine, February 1, 2021, at https://www.afcea.org/signal-media/growing-importance-guam.

【5】Mats Engman and Larissa Stünkel, “The Question of Guam: A Pivotal Island’s Changing Realities,” Institute for Security and Defense Policy, Dec. 18, 2020, at https://isdp.eu/publication/the-question-of-guam-a-pivotal-islands- changing-realities/.

【6】Statement of Adm. John C. Aquilino, U.S. Navy Commander, U.S. Indo-Pacific Command, before the House Committee on Appropriations Subcommittee on Defense, U.S. Indo-Pacific Command Posture, May 17, 2022, p. 13, at https://docs.house.gov/meetings/AP/AP02/20220517/114752/HHRG-117-AP02-Wstate-AquilinoJ-20220517.pdf.

【7】For example, then-INDOPACOM Commander and Navy Admiral Philip Davidson testified before the Senate Committee on Armed Services that, “Guam is a target today. It needs to be defended, and it needs to be prepared for the threats that will come in the future, because [it’s] clear to me that Guam is not just a place that we believe that we can fight from, as we have for many decades. We are going to have to fight for it in order to be able to do that..” For more information, see Senate Committee on Armed Services, “United States Indo-Pacific Command,” hearing video, March 9, 2021, at https://www.armed-services.senate.gov/hearings/21-03-09-united-states-indo-pacific-command. See also Mark Montgomery, Riki Ellison and Bradley Bowman, “Guam Needs Better Missile Defenses—Urgently,” Defense One, May 23, 2022, at https://www.defenseone.com/ideas/2022/05/guam-needs-better-missile-defensesurgently/367275/.

【8】Lee Jeong-ho, “China Releases Footage of ‘Guam killer’ DF-26 Ballistic Missile in ‘Clear Message to the US’,” South China Morning Post, January 28, 2019, at https://www.scmp.com/news/china/military/article/2183972/china-releases-footage-guam-killer-df-26-ballistic-missile-clear.

【9】DOD, Office of the Under Secretary of Defense (Comptroller)/Chief Financial Officer, Defense Budget Overview: United States Department of Defense Fiscal Year 2023 Budget Request, March 2022, p. 10, at https://comptroller.defense.gov/Portals/45/Documents/defbudget/FY2023/FY2023_Budget_Request.pdf#page=11.

【10】See, for example, Mats Engman and Larissa Stünkel, “The Question of Guam: A Pivotal Island’s Changing Realities,” Institute for Security and Defense Policy, December 18, 2020, at https://isdp.eu/publication/the-question-of- guam-a-pivotal-islands-changing-realities/.

【11】See Rebeccah Heinrichs, “Introduction,” in Defending Guam, Hudson Institute, July 2022, p. 7, at https://fsi- live.s3.us-west-1.amazonaws.com/s3fs-public/defendingguamjuly2022.pdf.  Oriana Skylar Mastro, “Defense, Deterrence, and the Role of Guam,” Stanford University, July 5, 2022, at https://aparc.fsi.stanford.edu/publication/defending-guam.

【12】See, for example, Sungmin Cho, “South Korea’s Taiwan Conundrum,” War on the Rocks, December 31, 2021, at https://warontherocks.com/2021/12/south-koreas-taiwan-conundrum/. Also see Kiyoshi Sugawa, “Should Japan Defend Taiwan?”, Responsible Statecraft, May 2023, at https://responsiblestatecraft.org/2023/05/02/should-japan-defend- taiwan/.

【13】“PLA plans are built around the expectation that it could eventually neutralize Guam, denying US forces the logistics and basing hub needed to sustain air and naval operations in defense of, for example, Taiwan.” See Bryan Clark, “Defending Guam,” Hudson Institute, July 2022, p. 14, at https://fsi-live.s3.us-west-1.amazonaws.com/s3fs-public/ defendingguamjuly2022.pdf.

【14】See Government Accountability Office, Missile Defense: Annual Goals Unmet for Deliveries and Testing (GAO-23- 106011), May 2023, p. 39, at https://www.gao.gov/assets/gao-23-106011.pdf. Also see Abraham Mahshie, “Guam Would Get Command Center with Integrated Air Picture in Missile Defense Agency Budget,” Air Force Magazine, March 25, 2022, at https://www.airforcemag.com/guam-to-get-command-center- with-integrated-air-picture-in-missile-defense-agency-budget/.

【15】Department of Defense, DOD transcript of MDA press briefing on FY2024 missile defense budget, March 14, 2023, at https://www.defense.gov/News/Transcripts/Transcript/Article/3328637/missile-defense-agency-officials-hold-a- press-briefing-on-president-bidens-fisc/.

【16】Army, “Air Defenders deploy first THAAD remote launch capability,” press release, March 16, 2022, at https://www.army.mil/article/254576/guam_air_defenders_deploy_first_thaad_remote_launch_capability.

【17】Center for Strategic and International Studies, Missile Defense Project, Terminal High Altitude Area Defense (THAAD), at https://missilethreat.csis.org/system/thaad/.

【18】CRS Report RL33745, Navy Aegis Ballistic Missile Defense (BMD) Program: Background and Issues for Congress, by Ronald O'Rourke.

【19】Government Accountability Office, Missile Defense: Annual Goals Unmet for Deliveries and Testing (GAO-23- 106011), p. 39, May 2023, at https://www.gao.gov/assets/gao-23-106011.pdf.

【20】Transcript, Senate Committee on the Armed Services, Tuesday, May 9, 2023, at https://www.armed- services.senate.gov/imo/media/doc/23-46_05-09-2023.pdf.

【21】Vice Adm. John Aquilino, testifying before the Senate Armed Services Committee on April 20, 2023.

【22】Department of Defense, 2022 Missile Defense Review, p. 7, available at https://media.defense.gov/2022/Oct/27/ 2003103845/-1/-1/1/2022-NATIONAL-DEFENSE-STRATEGY-NPR-MDR.PDF.

【23】Department of Defense Fiscal Year (FY) 2024 Budget Estimates, Missile Defense Agency Defense-Wide Justification Book Volume 2b of 2 Procurement, Defense-Wide, March 2023, p. 2b-125, at https://comptroller.defense.gov/Portals/45/Documents/defbudget/fy2024/budget_justification/pdfs/02_Procurement/ PROC_MDA_VOL2B_PB_2024.pdf. Additional detail may be available in classified versions of DOD budget justification documents.

【24】Jen Judson, “MDA’s plan to protect Guam relies on field-proven systems,” Defense News, March 30, 2022, at https://www.defensenews.com/congress/budget/2022/03/30/mdas-plan-to-protect-guam-relies-on-field-proven-systems/.

【25】Ibid.

【26】Ibid.

【27】Department of Defense Fiscal Year (FY) 2024 Budget Estimates, Missile Defense Agency Defense-Wide Justification Book Volume 2b of 2 Procurement, Defense-Wide, March 2023, see p. 2b 125.

【28】U.S. Space Force, U.S. Space Force Capabilities, at https://www.spaceforce.mil/About-Us/About-Space-Force/ Space-Capabilities/.

【29】S.Rept. 117-130, p. 286.

【30】General Services Administration, System for Award Management (SAM), Notice of Contract Opportunity, “Notice of Intent to Award Sole Source Aegis Guam Weapon System Engineering and Integration,” July 1, 2022, at https://sam.gov/opp/872785d477754f4b8f08b4a626a6991f/view.

【31】Missile Defense Agency, Enhanced Integrated Air & Missile Defense (EIAMD) for the defense of Guam, Environmental Impact Statement, at https://www.mda.mil/system/eiamd/eis.html.

【32】Missile Defense Agency, Enhanced Integrated Air & Missile Defense (EIAMD) for the defense of Guam, Environmental Impact Statement Fact Sheet, at https://www.mda.mil/system/eiamd/documents/eiamdeisfactsheet.pdf.

【33】Testimony of Missile Defense Director Vice. Adm. Jon Hill, in U.S. Congress, House Armed Services Committee, Subcommittee on Strategic Forces Hearing on Fiscal Year 2024 Budget Request for Missile Defense and Missile Defeat Programs, 118th Congress, April 18, 2023.

【34】Ibid.

【35】According to the Joint Explanatory Statement accompanying the FY2023 DOD Appropriations Act, “The update shall include: the status of environmental impact statements and site surveys required to support placement of weapons systems supporting the Defense of Guam, the upgrades to Guam’s infrastructure required to support the mission. acquisition schedules of anticipated weapons systems and corresponding deployment schedules of such systems. manning requirements for the Defense of Guam mission, and obligation and expenditure data on all funding related to the Defense of Guam. These updates shall be provided at an unclassified and classified level as required.” See Department of Defense Appropriations Act, 2023, Division C, p. 6, available at https://www.appropriations.senate.gov/ imo/media/doc/Division%20C%20-%20Defense%20Statement%20FY23.pdf#page=6.

【36】P.L. 117-263 §1660(a).

【37】P.L. 117-263 §1660(b).

【38】P.L. 117-263 §1660(c)(1).

【39】Steve Trimble, “Multibillion-Dollar Guam Defense Poses New Missile Defense Challenges,” Aviation Week, March 30, 2023, at https://aviationweek.com/defense-space/missile-defense-weapons/multibillion-dollar-guam- defense-poses-new-missile-defense. For additional analysis of the effectiveness of missile defense systems, see below, “Issues for Congress” section and “Defense of Guam” subsection.

【40】MDA Fact sheet reports Overall Test Record: 86 of 105 hit-to-kill intercept attempts have been successful across all programs since the integrated system began development in 2001. This record includes attempts by Aegis Ballistic Missile Defense (BMD), Ground-based Midcourse Defense (GMD), Terminal High Altitude Area Defense (THAAD), and PATRIOT Advanced Capability-3. See MDA Fact Sheet, January 17, 2019, at https://www.defense.gov/Portals/1/ Interactive/2018/11-2019-Missile-Defense-Review/ballistic-missile-defense-intercept-flight-test-record- UPDATED.pdf.

【41】See GAO, “Missile Defense: Annual Goals Unmet for Deliveries and Testing,” May 2023, at https://www.gao.gov/ products/gao-23-106011. Also see John F. Tierney, “We May Not Be Able to Stop a North Korean Missile,” New York Times, June 1, 2017. Also see Jaganath Sankaran, Steve Fetter, Defending the United States: Revisiting National Missile Defense against North Korea. International Security 2022, 46 (3): 51–86, at https://doi.org/10.1162/ isec_a_00426.

【42】Michael O’Hanlon, “Can China Take Taiwan?”, Brookings Institution, August 2022, at https://www.brookings.edu/ wp-content/uploads/2022/08/Can-China-Take-Taiwan-v5.pdf.

【43】“2022 Missile Defense Review” Fact Sheet, at https://media.defense.gov/2022/Oct/27/2003103921/-1/-1/1/ MISSILE-DEFENSE-REVIEW-MDR-FACTSHEET.PDF. Full report available at https://media.defense.gov/2022/Oct/ 27/2003103845/-1/-1/1/2022-NATIONAL-DEFENSE-STRATEGY-NPR-MDR.PDF.

【44】Michael O’Hanlon, “Can China Take Taiwan?”, Brookings Institution, August 2022, p. 17, at https://www.brookings.edu/wp-content/uploads/2022/08/Can-China-Take-Taiwan-v5.pdf.

【45】Congressional Budget Office, “National Cruise Missile Defense: Issues and Alternatives,” Feb. 9. 2021, p. 11 at https://www.cbo.gov/system/files/2021-02/56950-CMD.pdf.

【46】The Center for Arms Control and Non-proliferation estimates that interceptor missiles for Ground-Based Midcourse Defense (GMD) system that the United States’ anti-ballistic missile system uses for intercepting incoming warheads in space has been effective 55% of the time in highly-scripted tests. To reach a confidence level of at least 90%, three interceptors would need to be fired at a single warhead. See https://armscontrolcenter.org/issues/missile-defense/gmd- frequently-asked-questions/.

【47】Congressional Budget Office, “National Cruise Missile Defense: Issues and Alternatives,” February 2021, at https://www.cbo.gov/system/files/2021-02/56950-CMD.pdf.

【48】Ibid., p. 40.

【49】Ibid., p. 2.

122 Department o

【50】Department of Defense, 2022 Missile Defense Review, p. 12, available at https://media.defense.gov/2022/Oct/27/ 2003103845/-1/-1/1/2022-NATIONAL-DEFENSE-STRATEGY-NPR-MDR.PDF.