Trump’s Iron Dome for America is ambitious. It also has some serious technology and policy flaws

In his early days in office, President Donald Trump proposed a program to develop and eventually deploy an “Iron Dome for America.” The proposal is essentially a comprehensive antimissile and air defense system for the US homeland against future threats of attacks from ballistic, hypersonic, and advanced cruise missiles, as well as other advanced aerial attacks “from peer, near-peer, and rogue adversaries.”—read Russia, China, and North Korea, respectively.^[1]

To develop this program, President Trump tasked the US defense community with submitting within 60 days—by the end of March—a “reference architecture, capabilities-based requirements, and an implementation plan for the next-generation missile defense shield.”^[2]

The Trump administration’s ambitious plans for nationwide defenses deserve serious scrutiny about whether they are feasible—from the standpoint of available and foreseeable technology and cost—and desirable, from the standpoint of deterrence stability.

Technology and cost. According to the Trump administration, the required integrated air and missile defense architecture should include a whole portfolio of development and deployment plans, including for the “hypersonic and ballistic tracking space sensor layer,” proliferated space-based interceptors capable of missile boost-phase intercept, underlayer and terminal-phase intercept capabilities postured to defeat an attack on US population centers, a custody layer of sensing capabilities in the “proliferated warfighter space architecture,” and capabilities to defeat missile attacks prior to missile launch. In addition, the comprehensive plan must include a secure supply chain for all components with next-generation resilience and security features, as well as the development and deployment of “non-kinetic” capabilities to “augment the kinetic defeat of ballistic, hypersonic, advanced cruise missiles, and other next-generation aerial attacks.”^[3]

In sum, the proposed integrated defense system would include at least four layers, consisting of interceptors and a variety of space and land-based support systems for intelligence and warning, attack assessment, battle management, and command, control, and communications, together with trans- and-or post-attack response.

The interceptor layers are usually referred to, respectively, as boost, post-boost, midcourse, and terminal defenses. During the Cold War, history was unkind to advocates for strategic homeland missile defenses because the capabilities of ballistic missile offenses exceeded those of defenses both qualitatively and quantitatively. This meant that even the best performing antimissile defenses could be destroyed or otherwise negated in their effects by attackers at a fraction of the cost of deploying defenses. Defenses were therefore not “cost-effective at the margin.” Early efforts to develop anti-ballistic missile defenses—including the Safeguard and Sentinel—in the 1970s and the more ambitious “strategic defense initiative” or “star wars” proposals in the 1980s, proved to be more aspirational than operational in their impact.

Even after the end of the Cold War, the United States continued research and development efforts to deploy strategic ballistic missile defenses.^[4] President George H.W. Bush’s “brilliant pebbles” envisioned deployable space-based interceptors, but more modest efforts during the Bill Clinton and George W. Bush administrations resulted in ground-based midcourse defenses deployed in Alaska and California. These systems were deemed suitable for deflecting or destroying light attacks from rogue states like North Korea or accidental launches. The George W. Bush administration terminated the US participation in the Anti-Ballistic Missile Treaty of 1972, a cornerstone for US arms control that signaled to the Soviets that the United States might seek to overturn stable deterrence based on assured retaliation if defense technologies improved.

Under the Barack Obama, the first Donald Trump, and the Joe Biden administrations, the US Missile Defense Agency continued its efforts to improve the performances of ballistic missile defense intercept and supporting technology for battle management, command, control, and communications. Testing results were sometimes positive and at other times disappointing, relative to the objective of defending the entire US homeland’s population. Meanwhile, offensive systems continued marching ahead, with deployments of hypersonic weapons, boost-glide delivery systems, and maverick new weapons bruited by Russian President Vladimir Putin, including nuclear-powered, nuclear-armed torpedoes and air-launched ballistic missiles of various ranges.^[5]

The balance of terror between new and foreseeable defenses compared to offenses continued to be uncertain. But, for decades, defenses that would overturn the deterrence regime based on secure second-strike capability—compared to a regime based on defensive nullification of first strike—remained a futuristic possibility instead of a present reality.

Advocates for improved strategic antimissile and air defenses also face the challenge of anticipated cost for developing and deploying continental population defenses.

The US defense budget, including funds already committed to the modernization of the strategic nuclear triad—land-based intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and heavy bombers—is coming close to a trillion dollars in fiscal 2025. It is already arguable whether all ICBMs, SLBMs, bombers, and upscaled battle management, command, control and communications required for the next-generation strategic offensive weapons—by both the Biden and (presumably) the second Trump administrations—are affordable or even necessary.^[6]

The United States has also committed to an expensive modernization plan for the nuclear-weapon industrial complex. Beyond nuclear modernization, Pentagon expectations also include newer generations of conventional forces for the five armed services. The development and deployment of newer generations of integrated air and missile defenses, therefore, will add to the sticker shock inherent in other planned or proposed defense-related systems.

Strategy and deterrence stability. Even if they were technically feasible and affordable, these futuristic strategic defenses would impact deterrence stability, including through first strike capability and arms racing.

Should one member of the strategic nuclear top tier—China, Russia, or the United States—leapfrog into a newer generation of defenses while the other two remained locked into earlier technology, the first mover could dominate the deterrence spectrum. However, the first mover in this scenario would not be able to exploit its head start for very long because others would be motivated to catch up as soon as possible, leading to a new strategic nuclear arms race. It is not clear how the first mover could exploit its temporary advantage. Unlike with conventional weapons, the “winning” of a large nuclear war is a self-defeating exercise. Even a very small percentage of defense “leakage” by a first striker who is also supported by next-generation missile defenses could inflict historically unprecedented and socially unacceptable damage on the attacker’s own society.

Moreover, even the most demanding tests and exercises under artificial conditions cannot capture the total effects of nuclear war on the armed forces and societies of two belligerents. Another impact to deterrence strategies from improved strategic defenses is the likelihood that the great powers will move into next-generation defenses more or less simultaneously. This would result in a standoff among the United States, Russia, and China at unprecedentedly high levels of expenditure and uncertainty.

To avoid future improvements in antimissile and air defenses that lead to the next nuclear crisis, the United States (and other defense planners) could seek to defend the deterrence systems instead of the population. That is, the new defenses could be arranged to protect against a counterforce attack on military assets, rather than seeking to stop a countervalue attack on population centers. Although counterintuitive, this option would lead to more strategic stability.

If stable deterrence rests on ensuring a second-strike capability for the country that is attacked, more certainty about nuclear force survivability must be the preferred path. In the United States, for example, missile defenses could be deployed to improve the expected survivability of ICBMs, especially if the US deterrent continues to rely on silo basing for this component. Adding mobility to some portion of the land-based missile force would serve the same goal. All US strategic nuclear forces would presumably benefit from boost or post-boost defenses that nullify attacking missiles either before launch or almost immediately thereafter. These missions for the next generation of missile and air defenses would be more feasible than protecting the entire United States territory or the North American continent from large salvos of nuclear missiles.

Another concern that affects deterrence stability: The space-based components of any future missile and air defenses would themselves have to be defended. For example, the United States would have to deploy a force of defensive satellites to deter or deflect ground- or space-based anti-satellite weapons that would otherwise destroy vital components of the US warning, assessment, and command and control systems.

Finally, improved defenses would pose further challenge for nuclear arms control. The New Strategic Arms Reduction Treaty (New START)—the only bilateral nuclear arms control agreement between the United States and Russia—is set to expire in February 2026, and no follow-on treaty is in sight. Although preliminary conversations between Washington and Moscow about the next steps in arms control are no doubt taking place already behind closed doors, the war in Ukraine presents a major obstacle to formal arms control talks. Nevertheless, the second Trump administration should consider at least a temporary extension of New START’s limits on strategic weapons and launchers until another arms control regime can be devised and agreed upon.^[7]

A future arms control agreement between the two historic foes will have to consider the problem of non-strategic or tactical nuclear weapons and as next-generation threats to strategic stability—including potential conflicts in space, cyberwar, advanced hypersonic weapons, and improved missile defenses^[8]—as well as possibly a new player too: China.

Improved defenses, not offenses. As technologies for strategic missile defense will certainly improve over the next decade, offenses will not stand still. Improved missile and air defenses could add a layer of deterrence by denial to the existing dominant paradigm of deterrence by threat of assured retaliation.

Israel has already deployed impressive defenses against short- and medium-range missiles. But continental defenses that can provide perfect—or even near-perfect—protection for the US homeland are further off, if they are at all feasible. Such improved nationwide defenses will require enormous financial resources, posing many challenges to deterrence and arms race stability. The danger of a two- or three-sided great power competition over strategic offensive and defensive technologies is already apparent. To make things worse, the integration of next-generation cyber and space-based weapons, including those driven by innovation in artificial intelligence, into various combinations of offenses and defenses will also impact deterrence stability.

Technology potlatch and unsustainable arms races in deployed weapons and launchers are sure to subvert deterrence stability and strategic foresight that only a new arms control regime that includes discussion of missile defenses can rein in.

Notes

[1] President Donald J. Trump, The Iron Dome for America, Executive Order (Washington, D.C.: The White House, January 27, 2025), https://www.whitehouse.gov/presidential-actions/2025/01/the-iron-dome-for-america/

[2] Trump, The Iron Dome for America.

[3] Trump, The Iron Dome for America. See also: Rebeccah L. Heinrichs and General John Hyten, “The U.S. Must Upgrade Its Missile Defence to Deter Russia and China,” RUSI, April 2, 2024, https://www.rusi.org/explore-our-research/publications/commentary/us-must-upgrade-its-missile-defence-deter-russia-and-china; and Dr. Peppino DeBiaso and Ambassador Robert Joseph, “U.S. Homeland Missile Defense: Charting A Different Course,” May 6, 2024 (Fairfax, Va.: National Institute for Public Policy, Information Series, Issue No. 585), https://nipp.org/wp-content/uploads/2024/05/IS-585.pdf

[4] Andrew Futter, Ballistic Missile Defence and US National Security Policy: Normalization and Acceptance after the Cold War (New York: Routledge, 2013).

[5] For example, see: Vladimir Putin, Presidential Address to the Federal Assembly, March 1, 2018, in Johnson’s Russia List 2018 – #39 – March 1, 2018, davidjohnson@starpower.net , also http://kremlin.ru/events/president/news/56957.

[6] Stephen J. Cimbala and Lawrence J. Korb, “A game plan for dealing with the costly Sentinel missile and future nuclear challenges,” Bulletin of the Atomic Scientists, August 9, 2024, https://thebulletin.org/2024/08/a-game-plan-for-dealing-with-the-costly-sentinel-missile-and-future-nuclear-challenges/

[7] Arms control challenges and opportunities for the Trump II administration are discussed in: Jon B. Wolfsthal, “Trump wants a nuclear deal. Can he be the ultimate negotiator?”, Bulletin of the Atomic Scientists, January 31, 2025, https://thebulletin.org/2025/01/trump-wants-a-nuclear-deal-can-he-be-the-ultimate-negotiator/

[8] For example, see: Erik Gartzke and Jon R. Lindsay, “Thermonuclear cyberwar,” Journal of Cybersecurity (2017), pp. 1-12, https://doi.org/10.1093/cybsec/tyw017