Imagine a scenario where on January 20th, the new U.S. President, who just swore to defend the U.S. Constitution, approaches the podium to give the much-anticipated inaugural speech. Members of Congress, the Supreme Court, high-ranking military officers, family, and friends all take their seat. The new President grabs each side of the podium and looks up out at the audience. Countless households across the country listen to newscasters discuss the President’s campaign promises, policy goals, and the international challenges he will have to face over the next four years. The cameras zoom in on the President’s face as a member of the Secret Service approaches and whispers in his ear. Like magic, the President is spirited away within seconds. Shortly after, the Vice-President is escorted from the stage and members of Congress quickly follow suit. Newscasters discuss the various security concerns that would require an evacuation: fires, bomb threats, thwarted assassination attempts. Then, the news coverage goes offline while people are evacuating out of fear. After several minutes of trying to re-establish contact, ashen-faced newscasters finally report that a suspected low yield nuclear device has been detonated along Pennsylvania Avenue between the White House and the U.S. Capitol. In a literal flash, the newly sworn President, Vice-President, Speaker of the House, President Pro Tempore, unconfirmed cabinet members, the current heads of most federal agencies, and the majority of U.S. Congress are all now presumed dead. Soon, a shaky video of a mushroom cloud—recorded through a broken apartment window in Rosslyn, Virginia—dominates the news cycle. The few designated survivors and other remnants of the federal government scramble to establish lines of communication. When the new acting President speaks to the public that evening from a secure location, she asks U.S. citizens to remain calm. She tells them, truthfully, that plans are already being executed to recover from this event, and adversaries will not to be permitted to further exploit this horrific day.
In the years since 9/11, each branch of government issued policies establishing how the U.S. would maintain an enduring constitutional government in the wake of a catastrophic event such as a large regional weather disaster, high mortality pandemic, broad cyberattack on U.S. infrastructure, or a biological, chemical, radiological, or nuclear attack in the U.S. Regardless of the catastrophe, any plan to reestablish or maintain a functioning government requires resilient facilities and a reliable communication infrastructure. Luckily for the executive branch, there is already such infrastructure in place: the Nuclear Command, Control, and Communications (NC3) architecture. Often described as the “fourth leg” of the nuclear triad, NC3 architecture allows the President to authorize and direct the use of fielded nuclear forces.i However, despite the importance of NC3 architecture as a strategic deterrent and key component of sustaining an enduring constitutional government, the Department of Defense (DoD) has not treated these systems as a higher priority until recently. NC3 systems are aging and require modernization to account for current and future threats. For example, the Strategic Automated Command and Control System—a command and control system that manages intercontinental ballistic missiles, nuclear bombers, and tanker support aircraft—ran on a 1970s computing system and used eight-inch floppy disks until the system finally completed upgrades in 2019.ii Further NC3 modernization includes improvements to command posts, updating communications links to support shorter decisional timelines, and strengthening protection against cyber threats against the architecture. To ensure that NC3 architecture will be able to continue to withstand adversary threats, DoD needs to provide the funding, personnel, and other resources appropriate for the level of importance NC3 systems hold.
Continuity of Government
Continuity of Government, often confused with Continuity of Operations (COOP), is the coordinated effort within each of the executive, legislative, and judicial branches of the U.S. government to ensure that essential functions continue to be performed before, during, and after a catastrophic emergency.iii The eight national-level essential functions include preserving constitutional government, providing visible leadership, defending the country, maintaining foreign relations, protecting the homeland, providing emergency response and recovery, maintaining a stable economy, and providing critical government services.
Each branch of government has different critical functions in case of a catastrophic emergency. The executive branch maintains a recognizable authority providing direction and control over day-to-day management and implementation of emergency response and recovery operations. Some responsibilities for the executive branch also include establishing a line of succession through Department nominations, declaring emergencies, conducting emergency response operations, and safeguarding resources, facilities, and personnel. The legislative branch legislates emergency powers and authorities, including legal and budget authorities to implement government actions during emergency conditions that would not be otherwise authorized by law. The judicial branch decides on legal matters that arise during an emergency, such as the possible violations of Constitutional civil rights, and may provide flexibility in court rules or jurisdiction—such as allowing judges to hold court virtually or outside their typical jurisdiction—to maintain the judicial system throughout an emergency.iv Although this paper focuses on the executive branch, establishing secure and survivable facilities for leadership and staff to operate from and maintaining resilient communications are both necessary for all branches of government to perform its essential functions.
Command, Control, and Communications
The DoD plays a key role in COG efforts for the executive branch by maintaining national essential functions such as defending the country, protecting the homeland, and as part of its Defense Support of Civil Authorities mission, providing support for emergency response and recovery services. In particular, one of the President’s most valuable tools in COG operations is DoD’s NC3 architecture. Comprised of over 200 ground, space, and airborne systems spread across military services, combatant commands, and other DoD components.v In essence, NC3 is an interconnected web of facilities, equipment, communications, procedures, and personnelvi that includes fixed and mobile command posts; communications infrastructure such as land lines, satellite links, radars, radios, and receiving terminals in ground stations and strike vehicles; and early warning capabilities such as satellites, radars, sensors, and facilities to collect and interpret early warning information.vii
The NC3 system-of-systems’ primary mission is to link the President to nuclear forces, ensuring that the President is able to authorize and direct the use of nuclear weapons in case of a nuclear attack on the U.S. or its interests, or even for a preemptive attack by the U.S. against a nuclear weapon state.viii However, the command posts and supporting communications infrastructure is also used by the President, the Secretary of Defense, and other national senior leaders for command and control of military forces and to maintain situational and operational awareness throughout crisis and national emergency scenarios.ix Additionally, as part of the National Leadership Command Capability, the NC3 system is interoperable with and can share information between DoD’s command, control, and communications systems and the National Security and Emergency Preparedness capabilities for interagency, state, local, tribal and territorial governments.x
Command Posts
NC3 includes infrastructure that connects essential facilities—the primary and alternate command posts—with various executive branch departments and agencies. When needed, these command posts also act as COG facilities as they are continuously staffed and ready for use, providing the interagency coordination needed to address global and national events.xi The ground-based command posts have both day-to-day responsibilities and emergency functions. For example, the National Military Command Center (NMCC) in the Pentagon provides daily support to the President, Secretary of Defense, and the Chairman of the Joint Chiefs of Staff for monitoring nuclear forces and conventional military operations.xii In emergencies, however, the NMCC acts as the primary command and communications post for the Secretary of Defense and the Chairman of the Joint Chiefs of Staff, with the Alternative NMCC in Maryland acting as a backup if needed.xiii The Global Operations Center at U.S. Strategic Command (USSTRATCOM) is another command post used by the Commander of USSTRATCOM for command and control, daily management of strategic forces, and world event monitoring.xiv Other ground-based command posts include the North American Aerospace Defense Command headquarters, its alternate command post at Cheyenne Mountain Complex, and several types of land-based mobile backup command posts.xv
However, if the ground command centers are destroyed or incapacitated, operations can be transferred to airborne command posts such as the E-6B Airborne Command Post and the E-4B National Airborne Operations Center (NAOC).xvi For example, if the ground-based Global Operations Center is destroyed, the E-6B Airborne Command Post can act as a backup command post while maintaining its other missions—relaying presidential nuclear control orders to Navy nuclear submarines at sea or Air Force nuclear bombers in the air, and launching Minuteman III intercontinental ballistic missiles from ground-based silos.xvii Similarly, the E-4B NAOC acts as a backup survivable command, control, and communications center for the President and Secretary of Defense so the President can direct U.S. forces, execute emergency war orders, and coordinate actions by civil authorities.xviii In addition to its NC3 mission, the E-4B NAOC provides communications and command center capability to the Federal Emergency Management Agency after natural disasters.xix In that role, the E-4B NAOC can act as airborne support for DoD’s Defense Support of Civil Authorities mission. When executing that mission, DoD can temporarily employ the resources under the Department’s control—only under imminently serious conditions and when time does not permit approval from a higher authority—to save lives, prevent human suffering, or mitigate great property damage within the U.S.xx Consequently, the E-4B NAOC acts as a key airborne asset within COG infrastructure.
Communications Links
In addition to command posts, NC3 architecture relies on a network of communications systems. To ensure resiliency, this network has several redundancies such as multiple types of communications systems, different transmission pathways, and backup systems. Communications systems include terrestrial secure and non-secure phone lines, undersea cables, radios, communications terminals, relays between airborne command centers, and military and commercial satellites transmitting and receiving voice, video, and data. These transmitters and receivers use a range of the electromagnetic spectrum to operate, from extremely low frequency to extremely high frequency depending on the intended use. For example, ultra-high frequency is more effective transmitting through fog or cloud-cover than extremely high frequency, and extremely low frequency and very low frequency are the only frequencies capable of transmitting through water.xxi Because NC3 systems use a wide variety of platforms and means, communications are resilient against many national emergency scenarios, not just through a nuclear attack.
NC3 systems are designed to function when the supporting critical infrastructure is disabled or impaired, including electrical power, water, and transportation systems.xxii NC3 systems are also intended to function if other types of non-military support infrastructure are degraded, such as civilian communication facilities and pathways, civilian satellites and space-link ground stations, civilian computer server farms, and cloud computing networks.xxiii However, not every NC3 system is resilient against every type of threat. Generally, NC3 systems are designed to either be “thick line” or survivable “thin line” systems. Thick line systems are the facilities and communications used day-to-day to provide command and control over nuclear and other government operations.xxiv Thick line systems, although not intended to work during a nuclear attack, are less expensive, easier to use, and can be designed to recover in a post-nuclear environment. Thin line systems, on the other hand, provide the “assured, unbroken, redundant, survivable, secure and enduring” communications between the President and senior leaders.xxv Thin line systems are designed to withstand, operate through, or recover quickly from difficult and unpredictable adverse situations, conditions, and environments—up to and including a nuclear strike. Thin line communications links and ground terminals are more expensive, more inconvenient to use, and have lower data transmission rates, but are survivable through nuclear attacks because their electronic components have been hardened against nuclear radiation effects.xxvi These systems are also required to be hardened against electromagnetic pulses (EMP), work through nuclear scintillation, be jam-resistant, and be resilient against cyber-attacks. Moreover, because of the proliferation of thick line NC3 systems and the strict requirements that thin line NC3 systems have, NC3 systems are well-suited to support executive branch COG efforts, which would benefit from the hardened communications systems during non-nuclear emergencies that disrupt typical communications.
Resourcing and Need for Modernization
Although NC3 architecture is a key aspect of U.S. strategic deterrence and an immense asset to COG planning and execution, NC3 has not been treated as a priority until recently. In 2017 the Commander of Air Force Global Strike Command stated that he had “identified multiple areas [of NC3 systems] that have atrophied through decades of low prioritization.”xxvii In 2019, participants in an NC3 workshop at USSTRATCOM argued that NC3 lacks effective political and funding advocacy and that sustained bipartisan funding for NC3 should be treated as a “no brainer.” xxviii Only within the past decade have Congress and DoD begun to recognize that DoD should manage, fund, and modernize NC3 architecture the same way it does for other components of the U.S. nuclear deterrent, such as nuclear weapons and nuclear delivery systems.xxix
The NC3 systems operating today are decades old and quickly approaching their end of life. Former Commander of USSTRATCOM, Gen. John Hyten, even once described the NC3 architecture as “resilient, robust, and ancient.”xxx However, the age and interconnected nature of NC3 means that modernization is not as simple as a one-for-one replacement of systems. Moreover, threats have changed since these systems were put in place and new versions of old systems will not meet “21st century operational needs against 21st century threats.”xxxi For example, Russia is developing a new satellite designed to carry nuclear weapons on orbit, which could be used to wipe out “an entire orbit of assets crucial not just to the U.S., but the entire world.”xxxii Furthermore, China will likely field over 1,000 operational warheads by 2030, and is rapidly expanding its capabilities to counter NC3.xxxiii According to a DoD report to Congress:
“The [People’s Liberations Army] is developing, testing, and fielding capabilities intended to target U.S. and allied satellites, including electronic warfare to suppress or deceive enemy equipment, ground-based laser systems that can disrupt, degrade, and damage satellite sensors, offensive cyberwarfare capabilities, and direct-ascent anti-satellite (DA-ASAT) missiles that can target satellites in low Earth orbit (LEO).”xxxiv
Unfortunately, due to the age of legacy programs, DoD must first make significant investments into replacement NC3 command posts and communications systems before it can develop a Next-Generation NC3 architecture. For example, the Survivable Airborne Operations Center (SAOC) is a new aircraft that will be replacing the NAOC. The SAOC will be hardened against nuclear radiation and EMP effects, incorporate new communications antennas, and will integrate modern NC3 system and IT infrastructure.xxxv Additionally, DoD is developing replacement communications terminals that will function across different electromagnetic wavelengths. Several terminals will link through the Advanced Extremely High Frequency satellite constellation and are designed to operate through jamming, EMP effects, and nuclear scintillation.xxxvi Another communications terminal—a very low frequency receiver—will be able to communicate messages through nuclear effects and across very long distances. It will connect to ground- and air-based command posts, nuclear bombers, tankers, intercontinental ballistic launch control centers.xxxvii
Although necessary, modernizing equipment and increasing the connectivity of the networked systems can introduce new cyber vulnerabilities. Fortunately, DoD has identified the need to ensure the cybersecurity of NC3 and continuity of government communications. DoD’s command, control, and communications strategy even includes a line of effort to incorporate dedicated cybersecurity sensors and monitoring equipment that can detect a cyberattack and mitigate the operational risks before a system is degraded or compromised.xxxviii As part of this effort, the DoD should adopt adaptable and robust cybersecurity measures to prevent internal or external disruptions to NC3. These could include but are not limited to software and network protections, data protections, hardware protections, security and access controls, and incorporating “security by design.”xxxix
Next-Generation NC3
Once DoD replacement efforts are complete, the DoD plans to finally reinvent the NC3 system as part of a “Next-Generation” NC3 architecture. Since 2018, the NC3 Enterprise Center has been developing and evaluating potential NC3 architectures as well as different approaches for modernization.xl As DoD considers its options for future architecture, the DoD must also make decisions about that structure that will have down-stream effects on every NC3 system. The DoD will need to consider whether it prefers NC3 systems entangled with other communications systems, making them dual use; or if the systems should be distributed, diversified, and disaggregated. The DoD will need to decide to what extent it will make use of commercial technology and assets, and what modifications those assets might need. For each system and decision, DoD will need to determine the impact that system and decision will have on interoperable NC3 system and ensure that there are no gaps in capability.
For new communications systems, such as the Evolved Strategic Satellite Communications (ESS) program that will replace the Advanced Extremely High Frequency satellite, DoD will need to consider whether to shift its acquisition pathway strategies. While NC3 programs have historically been major defense acquisition programs acquired under what is now the major capability acquisition pathway, the urgent need and smaller size of NC3 programs may make them more suited to the faster-paced middle-tier of acquisition pathway. However, the faster pathway may require more resourcing to mitigate operational risk during a system’s design, testing, and production. Moreover, DoD will need to ensure that regardless of the acquisition approach, each survivable NC3 system meets the strict requirements for nuclear survivability.
Developing the Next-Generation NC3 architecture will not come without significant investments in funding, time, and personnel. However, the prior lack of investment in NC3 and its remaining importance to COG means that NC3 should be prioritized more than ever. After all, NC3 does not represent a large part of the U.S. defense budget. According to the Congressional Budget Office, the projected cost of NC3 over the 2023-2032 period is $59 billion—which doesn’t include an additional $58 billion needed for early warning satellite systems—representing less than one percent of the estimated defense budget during that timeframe.xli Given the limited cost of Next-Generation NC3, then, DoD’s investment in NC3 is more an extension of political will—by Congress, by the President, and by the Secretary of Defense. NC3 must be modernized beyond box-for-box system replacements to meet the significant changes and challenges presented by evolving geopolitical environments and technical capabilities. Moreover, the DoD must keep focus and commit to sustained, adequate resourcing of Next-Generation NC3 architecture so that NC3 can keep pace with not only modern threats but threats ten years from now.
The author is responsible for the content of this article. The views expressed are the author’s own and do not reflect the official policy or position of the U.S. Government Accountability Office, the National Intelligence University, the Office of the Director of National Intelligence, the U.S. Intelligence Community, or the U.S. Government.
References:
i Williams, Heather. “Updating Nuclear Command, Control, and Communication.” Center for Strategic and International Studies. Washington, DC, December 2024.
ii U.S. Government Accountability Office. “Information Technology: Federal Agencies Need to Address Aging Legacy Systems.” GAO-16-468. Washington, DC: May 25, 2016; Stack, Liam. “Update Complete: U.S. Nuclear Weapons No Longer Need Floppy Disks.” New York Times, October 24, 2019. https://www.nytimes.com/2019/10/24/us/nuclear-weapons-floppy-disks.html
iii “Guide to Continuity of Government: For State, Local, Tribal and Territorial Governments.” FEMA, July 2021; Department of Homeland Security, Homeland Security Council. “National Continuity Policy Implementation Plan.” Washington, DC, August 2007.
iv “Guide to Continuity of Government: For State, Local, Tribal and Territorial Governments.” FEMA, July 2021;
v Ibid.
vi Ibid.
vii Larsen, Jeffrey. “Nuclear Command, Control, And Communications: US Country Profile.” Technology for Global Security (T4GS) Special Reports, August 22, 2019. https://www.tech4gs.org/nc3-systems-and-strategic-stability-a-globaloverview.html
viii Fink, Anya L. “Defense Primer: Nuclear Command, Control, and Communications (NC3).” no. IF11697 Version 2. Congressional Research Service: In Focus, October 3, 2024.
ix Fink, Anya L. “Defense Primer: Nuclear Command, Control, and Communications (NC3).” no. IF11697 Version 2. Congressional Research Service: In Focus, October 3, 2024;
x Department of Defense. “C3: Command, Control, and Communications Modernization Strategy.” September 2020; U.S. Air Force, Deputy Chief of Staff for Strategic Deterrence and Nuclear Integration. “Air Force Nuclear Command, Control, And Communications (NC3).” Nuclear, Space, Missile, Command and Control. no. AFI13-550. April 16, 2019; Joint Chiefs of Staff. “Joint Communications System.” Joint Publication 6-0. October 4, 2019.
xi Joint Chiefs of Staff. “Joint Communications System.” Joint Publication 6-0. October 4, 2019.
xii Office of the Deputy Assistant Secretary of Defense for Nuclear Matters, “Chapter 2: Nuclear Weapons Employment Policy, Planning, and NC3,” in Nuclear Matters Handbook 2020 [Revised], 14-21, Washington, DC: Department of Defense, 2020.
xiiiOffice of the Deputy Assistant Secretary of Defense for Nuclear Matters, “Chapter 2: Nuclear Weapons Employment Policy, Planning, and NC3,” in Nuclear Matters Handbook 2020 [Revised], 14-21, Washington, DC: Department of Defense, 2020; Larson, Jeffrey A. “Nuclear Command, Control, and Communications: An Overview.” In Nuclear Command, Control, and Communications: A Primer on US Systems and Future Challenges, edited by James J. Wirtz and Jeffrey A. Larson. Washington, DC: Georgetown University Press, 2022.
xiv Office of the Deputy Assistant Secretary of Defense for Nuclear Matters, “Chapter 2: Nuclear Weapons Employment Policy, Planning, and NC3,” in Nuclear Matters Handbook 2020 [Revised], 14-21, Washington, DC: Department of Defense, 2020
xv Larson, Jeffrey A. “Nuclear Command, Control, and Communications: An Overview.” In Nuclear Command, Control, and Communications: A Primer on US Systems and Future Challenges, edited by James J. Wirtz and Jeffrey A. Larson. Washington, DC: Georgetown University Press, 2022.
xvi Ibid.
xvii Office of the Deputy Assistant Secretary of Defense for Nuclear Matters, “Chapter 2: Nuclear Weapons Employment Policy, Planning, and NC3,” in Nuclear Matters Handbook 2020 [Revised], 14-21, Washington, DC: Department of Defense, 2020.
xviii U.S. Air Force. “E-4B” Current as of June 2024. https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104503/e-4b/; Fink, Anya L. “Defense Primer: Nuclear Command, Control, and Communications (NC3).” no. IF11697 Version 2. Congressional Research Service: In Focus, October 3, 2024.
xix U.S. Air Force. “E-4B” Current as of June 2024. https://www.af.mil/About-Us/Fact-Sheets/Display/Article/104503/e-4b/; Fink, Anya L. “Defense Primer: Nuclear Command, Control, and Communications (NC3).” no. IF11697 Version 2. Congressional Research Service: In Focus, October 3, 2024.
xx Joint Chiefs of Staff. “Defense Support of Civil Authorities.” Joint Publication 3-28. October 29, 2018.
xxi Crook, Matthew R. “Space Architecture for NC3: Systems and Technologies.” In Nuclear Command, Control, and Communications: A Primer on US Systems and Future Challenges, edited by James J. Wirtz and Jeffrey A. Larson. Washington, DC: Georgetown University Press, 2022.
xxii Deptula, David A., William A. LaPlante, with Robert Haddick. “Modernizing U.S. Nuclear Command, Control, and Communications,” Mitchell Institute and MITRE. Arlington, VA: The Mitchell Institute for Aerospace Studies, February 2019.
xxiii Ibid.
xxiv Office of the Deputy Assistant Secretary of Defense for Nuclear Matters, “Chapter 2: Nuclear Weapons Employment Policy, Planning, and NC3,” in Nuclear Matters Handbook 2020 [Revised], 14-21, Washington, DC: Department of Defense, 2020.
xxv Ibid.
xxvi Crook, Matthew R. “Space Architecture for NC3: Systems and Technologies.” In Nuclear Command, Control, and Communications: A Primer on US Systems and Future Challenges, edited by James J. Wirtz and Jeffrey A. Larson. Washington, DC: Georgetown University Press, 2022.
xxvii Rand, Robin. “Presentation to the Senate Armed Services Committee: Strategic Forces Subcommittee.” June 7, 2017.
xxviii Hersman, Rebecca K.C., Eric Brewer, and Suzanne Claeys. “NC3: Challenges Facing the Future System.” CSIS: Deep Dive Debrief. Center for Strategic & International Studies (CSIS), July 2020.
xxix Malley, Michael S. “NC3 Modernization: Progress and Remaining Changes.” In Nuclear Command, Control, and Communications: A Primer on US Systems and Future Challenges, edited by James J. Wirtz and Jeffrey A. Larson. Washington, DC: Georgetown University Press, 2022.
xxx Military Assessment of Nuclear Deterrence Requirements, House Armed Services Committee (March 8, 2017), video 44:00, https://armedservices.house.gov/legislation/hearings/military-assessment-nuclear-deterrence-requirements
xxxi Malley, Michael S. “NC3 Modernization: Progress and Remaining Changes.” In Nuclear Command, Control, and Communications: A Primer on US Systems and Future Challenges, edited by James J. Wirtz and Jeffrey A. Larson. Washington, DC: Georgetown University Press, 2022.
xxxii Narang, Vipin. “’Nuclear Threats and the Role of Allies’: Remarks by Acting Assistant Secretary of Defense for Space Policy Dr. Vipin Narang at CSIS.” Speech, Center for Strategic and International Studies. August 1, 2024. https://www.defense.gov/News/Speeches/Speech/Article/3858311/nuclear-threats-and-the-role-of-allies-remarks-by-acting-assistant-secretary-of/
xxxiii Narang, Vipin. “’Nuclear Threats and the Role of Allies’: Remarks by Acting Assistant Secretary of Defense for Space Policy Dr. Vipin Narang at CSIS.” Speech, Center for Strategic and International Studies. August 1, 2024. https://www.defense.gov/News/Speeches/Speech/Article/3858311/nuclear-threats-and-the-role-of-allies-remarks-by-acting-assistant-secretary-of/;
xxxiv US Department of Defense, “Space Policy Review and Strategy on Protection of Satellites,” September 2023, 2-3, https://media.defense.gov/2023/Sep/14/2003301146/-1/-1/0/
xxxv Hadley, Greg. “Air Force Awards $13 Billion Contract for New ‘Doomsday’ Planes.” Air & Space Forces Magazine. April 28, 2024. https://www.airandspaceforces.com/air-force-13-billion-contract-doomsday-plane-saoc/ ; Losey, Stephen. “Sierra Nevada gears up to build US Air Force ‘doomsday’ planes.” Defense News. May 31, 2024. https://www.defensenews.com/air/2024/05/31/sierra-nevada-gears-up-to-build-us-air-force-doomsday-planes/
xxxvi Deptula, David A., William A. LaPlante, with Robert Haddick. “Modernizing U.S. Nuclear Command, Control, and Communications,” Mitchell Institute and MITRE. Arlington, VA: The Mitchell Institute for Aerospace Studies, February 2019.
xxxvii Office of the Deputy Assistant Secretary of Defense for Nuclear Matters, “Chapter 2: Nuclear Weapons Employment Policy, Planning, and NC3,” in Nuclear Matters Handbook 2020 [Revised], Washington, DC: Department of Defense, 2020.
xxxviii Department of Defense. “C3: Command, Control, and Communications Modernization Strategy.” September 2020.
xxxix Afina, Yasmin, Calum Inverarity, and Beyza Unal. “Ensuring Cyber Resilience in NATO’s Command, Control and Communication Systems.” Chatham House: Royal Institute of International Affairs, July 2020.
xl Office of the Deputy Assistant Secretary of Defense for Nuclear Matters, “Chapter 2: Nuclear Weapons Employment Policy, Planning, and NC3,” in Nuclear Matters Handbook 2020 [Revised], 14-21, Washington, DC: Department of Defense, 2020.
xli Congressional Budget Office. “Projected Costs of U.S. Nuclear Forces, 2023-2032.” July 2023. https://www.cbo.gov/publication/59365
