The Delusions and Dangers of Missile Defense

By September 2023
By Jaganath Sankaran

The U.S. doctrine and posture on missile defense are in rapid flux.

The proliferation of advanced missile systems to regional actors has triggered an expansion of missile defense systems. Furthermore, as arms control agreements fade away and great-power competition reemerges, long-standing principles undergirding the link between homeland missile defense and strategic stability are being challenged. For instance, the House of Representatives draft of the 2024 National Defense Authorization Act (NDAA) has argued for amending U.S. doctrine to declare that homeland missile defense systems are now vital “to maintain a credible nuclear capability as the foundation of strategic deterrence.”1 Such a declaration would constitute a massive departure from the prevailing understanding of the role or, more accurately, the denial of a role for homeland missile defense in securing nuclear deterrence against near-peer adversaries.

China’s large arsenal of ballistic and cruise missiles, including this Dong Feng-26 (DF-26) intermediate-range ballistic missile, are among the threats driving the United States to invest increased spending on missile defense systems. (Photo by Xinhua/Cha Chunming via Getty Images)Historically, U.S. nuclear doctrine has insisted that homeland missile defense does not and cannot affect the strategic deterrent between major nuclear powers. For instance, the 2022 Missile Defense Review explicitly acknowledges that “the United States will continue to rely only on strategic deterrence” against Russia and China.2 Similar commitments have been consistently reiterated across administrations and by the U.S. Congress over several decades.

These doctrinal commitments are also enshrined in bilateral agreements, including the 2010 New Strategic Arms Reduction Treaty, which recognized the existence of an inverse interrelationship between strategic deterrence and homeland missile defense. That is to say, as an adversary state obtains more effective homeland defense, its ability to execute a disarming nuclear first strike increases. The treaty notes that
the “interrelationship will become more important as strategic nuclear arms are reduced.”3

The attempt to upend the doctrine is a hawkish stance and, in all likelihood, will fail. The Biden administration recognizes that such a move would portend significant adverse effects on strategic stability among the United States, Russia, and China. The administration has objected to the amendment to missile defense policy, noting in a Statement of Administration Policy that the proposed policy change will undermine strategic deterrence with Russia and China and overturn “two decades of well-established” policy on homeland missile defense.4 Despite the political desire to preserve the “well-established” policy, however, growing U.S. attempts to build a technologically advanced architecture of missile defense systems directly undermine strategic stability even if the intent is not to do so.

A Growing Threat

Various regional missile threats pose significant challenges for U.S. troops and allied states. A 2020 report by the National Air and Space Intelligence Center and the Defense Intelligence Ballistic Missile Analysis Committee declared that cruise and ballistic missiles would be used as “instruments of coercion” by adversaries seeking to end a crisis or a conflict with the United States or its allies on preferential terms.5

Three states—China, Iran, and North Korea—lie at the core of U.S. concern. Iran has the largest rocket, missile, and drone arsenal in the Middle East. A 2019 U.S. Defense Intelligence Agency report notes that Iran developed its arsenal to dissuade its regional adversaries and the United States.6 In June 2022, top military officials from Egypt, Israel, Jordan, Qatar, and Saudi Arabia secretly met U.S. military commanders to discuss ways to “coordinate against Iran’s growing missile” arsenal.7 North Korea has amassed a large arsenal of missiles targeting U.S. regional and allied targets throughout the Asia-Pacific region. These missiles could inflict significant destruction and death on South Koreans and deployed U.S. personnel. China possesses a large arsenal of ballistic and cruise missiles intended to generate “coercive political and military advantages in a regional crisis or conflict.”8 The bulk of China’s missile arsenal can reach regional airbases and port facilities that would be important in a regional military contingency involving the United States and its allies.

All these threats drive the impulse of U.S. policymakers to invest more in missile defense. The Biden administration has requested $29.8 billion for missile defense systems in the fiscal year 2024 budget, an increase of $5.1 billion from the previous year.9 The request includes $3.3 billion for the Ground-Based Midcourse Defense (GMD) homeland defense system, which is aimed at limited rogue threats such as North Korean intercontinental ballistic missiles (ICBMs). The other requests are directed at regional and theater missile defense, including $1.8 billion for the Aegis ballistic missile defense program, $574 million for the Terminal High Altitude Area Defense (THAAD) program, and $567 million for an integrated air and missile defense system in Guam.10

Yet, despite these investments, in reality the relative cost of defense is too high and favors the offense.11 It is much easier to innovate for the offense and defeat the defense with simpler tactics. The war in Yemen between the Houthi rebels and the Saudi Arabia-led coalition provides an illustration. The Saudis have relied on Patriot missile defense systems to defend against Houthi missiles. Each Patriot missile defense interceptor, however, costs approximately $1 million whereas the “flying lawn mowers” launched by the Houthis cost less than $10,000 each.12

Furthermore, the Houthis have found ingenious ways to defeat the Patriot systems by using drones to strike and damage the systems and then launching missiles before they could be fixed.13 A Saudi spokesperson has observed that “there is no country in the world being attacked with such amount of ballistic missiles.”14 The constant barrage of Houthi attacks has forced the Saudis to deplete their Patriot missile defense interceptor supply, requiring desperate efforts to replenish the inventory. Even for a wealthy state such as Saudi Arabia, missile defense systems offer short-term protection, not a long-term solution to missile strikes. Similarly, Russia’s never-ending use of missiles to bombard Ukraine demonstrates that missile defense can stall and weaken the thrust of the offense but cannot offer sustained protection.

The Perils of Unconstrained Missile Defense

The United States has spent more than $165 billion to experiment and produce the technological breakthroughs necessary to field an effective, limited homeland and regional missile defense system.15 Over the last two decades, the unconstrained experimentation has resulted in a globally distributed, technologically advanced architecture of missile defense interceptors, platforms, and sensors. Although these efforts have not shifted the advantage to the defense, they potentially can produce damaging consequences for strategic stability between major nuclear powers.

The Standard Missile-3 (SM-3) Block Interceptor, shown during a test over the Pacific Ocean in 2008, is among the systems being developed by the United States to defeat a threat from intercontinental ballistic missiles. (Photo by U.S. Navy via Getty Images)The architecture, in principle, portends the ability to realize a surprise breakthrough in strategic defensive capability against Russia and China. For instance, reacting to advances in North Korean ballistic missiles, the fiscal year 2018 NDAA mandated the U.S. Missile Defense Agency (MDA) to test the technological feasibility of the Standard Missile-3 (SM-3) Block IIA interceptor to defeat an ICBM threat.16 These interceptors initially were designed to defend against medium- and intermediate-range ballistic missiles. On November 16, 2020, the agency employed a ballistic missile defense-capable ship to launch an SM-3 IIA and intercept an ICBM-range missile.17 The use of these interceptors for homeland defense against North Korean ICBMs may now be de facto policy. In June 2021, Deputy Secretary of Defense Kathleen Hicks reportedly authorized the transfer of 11 SM-3 IIA interceptors from research to deployment after the successful flight test.18

The technological evolution in the performance of interceptors is further reinforced by a separate dedicated effort to advance the state-of-the-art sensor technologies supporting missile defense missions. The SPY-6(V)1 radar, performing a variety of missions including missile defense, originally had a programmatic requirement for a sensor to be 30 times more sensitive than the current SPY-1 radar deployed on ballistic missile defense-capable ships.19 Yet, the SPY-6(V)1 radar has turned out better than expected and is “nearly 100 times more sensitive” than the SPY-1 radar.20 Alternatively measured, the SPY-6(V)1 could track objects with similar signatures at approximately three times the range of SPY-1 radar. U.S. advances in missile defense radars have progressed alongside technological gains in space-based tracking and cueing.

Each of these technological capabilities, in its individual capacity, originated as a way to defend against regional threats, but the summation of these accumulated technological capabilities has a much larger strategic impact than their individual parts. A three-fold increase in the tracking range of the organic radar sensors of ballistic missile defense-capable ships armed with interceptors capable of homeland missile defense missions significantly expands the capabilities of these platforms. Additionally, the MDA has proposed a layered homeland defense architecture consisting of the GMD system augmented by underlayers of SM-3 IIA and THAAD interceptors.21

Such a layered homeland missile defense architecture may rapidly expand the number of interceptors and opportunities for interception from the tens to the hundreds. It could provide, in principle, a significant capability for strategic defense against Russian and Chinese missiles. A homeland defense shield buttressed by a shoot-look-shoot GMD system that can pursue two distinct intercept attempts, followed by the SM-3 Block IIA interceptors as an underlayer and THAAD interceptors for terminal defense, cannot reasonably be claimed to be limited.22 Such a multilayered missile defense architecture would be viewed as highly destabilizing and catalyze an arms race.

Rethinking Missile Defense

U.S. missile defense efforts have produced a worst-of-both-worlds situation. On the one hand, against increasingly sophisticated regional missile threats, the efforts to deploy a robust regional missile defense shield appear improbable. At the same time, the growing pace of North Korean capabilities and systemic U.S. technical failures raises severe doubts about the viability of the GMD homeland missile defense system.23 On the other hand, the accumulation of a range of technological capabilities to support the missile defense mission undermines strategic stability.

U.S. Secretary of Defense Robert McNamara, discussing U.S. fears of a Soviet technological breakthrough in missile defense systems in 1967, observed that it did not make “much difference what the evidence indicates…because I believe we must assume for planning” purposes that a system with the probable characteristic of a missile defense system can at some future point emerge as a capable defense.24 Throughout the 1960s, U.S. nuclear war planners espoused a greater-than-expected threat metric to offset any future Soviet technical breakthroughs in missile defense. Similarly, prudence requires Russian and Chinese analysts to assume any limited U.S. system is a stalking horse for a more substantial defense. If worst-case planning is the baseline to determine requirements for strategic deterrence, Russia and China could easily postulate imminent U.S. qualitative and quantitative breakthroughs.

A Russian Yars intercontinental ballistic missile launcher crosses Red Square during the Victory Day military parade in May 2022. (Photo by Alexander Nemenov/AFP via Getty Images)After the end of the Cold War, U.S. policymakers were willing to suspend the logic of strategic stability in the pursuit of missile defense. Yet, such a posture is no longer possible. The United States has declared the reemergence of great-power competition. The 2022 Nuclear Posture Review asserts the emergence of two major nuclear powers, Russia and China, as U.S. strategic competitors and potential adversaries. The review acknowledges “new stresses” on stability and deterrence.25 The pursuit of unconstrained missile defense systems is one of those stressors. U.S. efforts to maintain a viable homeland and regional missile defense have reached the point where the vector sum of the emerging capabilities of the various interceptors and sensors already surpass, in theory, the requirements of a highly capable homeland defense that could function against major nuclear powers.

A rethinking of the logic and purpose of the U.S. missile defense enterprise is urgently needed. First, the role of defensive and offensive forces against regional missile threats has to be reexamined in light of recent experiences, including the Russian war against Ukraine. Missile defense in a regional context may play niche roles, but it cannot be the essence of the U.S. deterrent and war-fighting strategy. Second, technology creep continues to erode the separation between regional and homeland systems. U.S. policymakers must institute clear limits to highlight the separation between these systems. Finally, policymakers also must explore arms control measures to constrain regional ballistic missile arsenals.

Although arms control diplomacy appears infeasible in the prevailing geopolitical environment, a treaty akin to the Intermediate-Range Nuclear Forces Treaty constraining ballistic missile proliferation and missile defense systems simultaneously would address the concerns of the United States, Russia, and China. Such arms control efforts may become viable in the future, and Washington must be prepared to seize any opening.


1. National Defense Authorization Act for Fiscal Year 2024, H.R. 2670, 118th Cong.
(2023) (House engrossed version),

2. U.S. Department of Defense, “2022 Missile Defense Review,” October 27, 2022, p. 5,

3. Treaty Between the United States of America and the Russian Federation on Measures for the Further Reduction and Limitation of Strategic Offensive Arms, April 8, 2010,

4. U.S. Office of Management and Budget, “Statement of Administration Policy: H.R. 2670 - National Defense Authorization Act for Fiscal Year 2024,” July 10, 2023, p. 4,

5. National Air and Space Intelligence Center and Defense Intelligence Ballistic Missile Analysis Committee, “2020 Ballistic and Cruise Missile Threat,” July 2020, p. 4,

6. Defense Intelligence Agency, “Iran Military Power: Ensuring Regime Survival and Securing Regional Dominance,” 2019, p. 30,

7. Michael R. Gordon and David S. Cloud, “U.S. Held Secret Meeting With Israeli, Arab Military Chiefs to Counter Iran Air Threat,” The Wall Street Journal, June 26, 2022.

8. Office of the U.S. Secretary of Defense, “2019 Missile Defense Review,” 2019, p. v,

9. Office of the Under Secretary of Defense, Comptroller/Chief Financial Officer, “United States Department of Defense Fiscal Year 2024 Budget Request,” March 2023, p. 7, For a comparison to the previous fiscal year, see Center for Arms Control and Non-Proliferation, “Fiscal Year 2024 Defense Budget Request Briefing Book,” April 4, 2023,

10. Center for Arms Control and Non-Proliferation, “Fiscal Year 2024 Defense Budget Request Briefing Book.” See also Office of the Under Secretary of Defense, Comptroller/Chief Financial Officer, “United States Department of Defense Fiscal Year 2024 Budget Request,

11. Jaganath Sankaran, “Missile Wars in the Asia Pacific: The Threat of Chinese Regional Missiles and U.S.-Allied Missile Defense Response,” Asian Security, Vol. 17, No. 1 (2021); Jaganath Sankaran, “Missile Defenses and Strategic Stability in Asia: Evidence From Simulations,” Journal of East Asian Studies,
Vol. 20, No. 3 (November 2020): 485-508.

12. Gordon Lubold, “Saudi Arabia Pleads for Missile-Defense Resupply as Its Arsenal Runs Low,” The Wall Street Journal, December 7, 2021. See also Ben Hubbard, Palko Karasz, and Stanley Reed, “Two Major Saudi Oil Installations Hit by Drone Strike, and U.S. Blames Iran,” The New York Times, September 14, 2019.

13. See Gordon, “Saudi Arabia Pleads for Missile-Defense Resupply as Its Arsenal Runs Low.”

14. Meg Wagner et al., “Trump Orders New Iran Sanctions After Saudi Attack,” CNN, September 18, 2019,

15. Justin Doubleday, “Ballistic Missile Defense Program Costs Rise to $164.9 Billion,” Inside the Pentagon, August 10, 2017.

16. Ronald O’Rourke, “Navy Aegis Ballistic Missile Defense (BMD) Program: Background and Issues for Congress,” CRS Report, RL33745, April 1, 2022, p. 12.

17. Megan Eckstein, “MDA to Use Destroyer USS John Finn for Defense-of-Hawaii Missile Intercept Test,” USNI News, August 5, 2020,; O’Rourke, “Navy Aegis Ballistic Missile Defense (BMD) Program,” p. 12.

18. Anthony Capaccio, “U.S. Navy Ships Close to Getting Interceptors That Could Stop an ICBM,” Bloomberg, June 22, 2021,

19. Jason Sherman, “Navy Determines SPY-6 Radar Three Times Stronger Than Original Requirement,” Inside Defense, May 3, 2019.

20. Ibid.

21. Jen Judson, “Missile Defense Agency Director Lays Out Hurdles in Path to Layered Homeland Missile Defense,” Defense News, August 18, 2020, See also U.S. Department of Defense, “Layered Homeland Missile Defense: A Strategy for Defending the United States,” n.d.,

22. In addition to these midcourse and terminal defenses, the U.S. Missile Defense Agency has developed and tested a variety of boost-phase missile defenses. See Jaganath Sankaran and Steve Fetter, “Defending the United States: Revisiting National Missile Defense Against North Korea,” International Security, Vol. 46, No. 3 (Winter 2021): 51-86; Jaganath Sankaran and Steve Fetter, “Reexamining Homeland Missile Defense Against North Korea,” The Washington Quarterly, Vol. 43, No. 3 (Fall 2020).

23. Sankaran and Fetter, “Defending the United States.”

24. Lawrence Freedman, US Intelligence and the Soviet Strategic Threat, 2nd ed. (Princeton: Princeton University Press, 1986), p. 96 (citing press conference of U.S. Secretary of Defense Robert McNamara on April 3, 1967).

25. U.S. Department of Defense, “2022 Nuclear Posture Review,” October 27, 2022, p. 4,

Jaganath Sankaran is an assistant professor at the Lyndon B. Johnson School of Public Affairs and a nonresident fellow at the Brookings Institution.