The announcement of Golden Dome in May 2025 has reinvigorated discussions around the often-maligned concept of space-based missile defenses. Ever since President Reagan’s 1983 speech announcing the Strategic Defense Initiative (SDI), space-based missile defenses have been opposed by some as unrealistic. Although SDI was successful in bankrupting the Soviet Union, many in Congress never viewed SDI as legitimately achievable. The noble aim of irradicating threats from intercontinental missiles has often been lost to those who seek to question not only the technical feasibility but also their impact on nuclear deterrence. Yet following the announcement of Golden Dome by President Trump, Congress allocated $25 billion for program development and initial deployment, suggesting the government is finally moving in the direction of supporting a robust homeland defense capability through the deployment of an SDI concept now technically ready for use: Brilliant Pebbles.
The fundamental aim of Golden Dome is to protect the United States from air or space-based missiles armed with a variety of warheads: nuclear, chemical, biological, or conventional. Golden Dome will be made available to key allies should they deem it necessary for their own defenses in an increasingly complex global security environment. However, the level of interest these allies have in negotiating the terms of missile defenses from the U.S. remains to be seen.
While moving beyond the technical development of SDI, Golden Dome is not ushering a new age of missile defense strategy. A national missile defense policy has been in place since the 1990s following a hotly debated period in Congress where a “placebo defense” was finally deployed. The term “placebo defense” was coined by prolific political strategist Dr. William Van Cleave, who advocated for a layered concept of missile defense while he was a member of “Team B.” Team B was commissioned by the-then Director of Central Intelligence, President George H.W. Bush for the purpose of providing the government with alternative intelligence assessments and policy guidance regarding the Soviet strategic threat.
Dr. Van Cleave first used the term “placebo defense” in lectures at the Department of Defense & Strategic Studies at Missouri State University in 1996. While not officially defined in any academic paper, “placebo defense” describes the U.S. policy of deploying limited missile defenses incapable of defending against significant ballistic missile attack from either Russia or China. Rather, such limited missile defenses instead minimize the threat by rogue states like North Korea and Iran. The goal in part was to silence the critics who claim the U.S. must at least be able to defend itself from those rogue nations more likely to launch one or two missiles at U.S. forces overseas, or key coastal areas of the country.
The Team B concept of layered missile defense was supported by former SDI officials who advocated for a space-based laser (SBL) system to provide the most effective method of intercepting ballistic missiles. While this would be ideal for balancing technical feasibility and overall program cost, SBLs were not supported by Congress and follow-on administrations. Valuable research and development have since been neglected, making SBLs unlikely achievable anytime soon.
Golden Dome is now poised to move forward with some of the Team B concepts and additional strategists since the 1990s. To move Golden Dome forward rapidly, it is time to reconsider Brilliant Pebbles, which is also referred to as Future Space-Based Interceptors. Designed by Lawerence Livermore National Laboratory, Brilliant Pebbles envisioned placing small space-based interceptors (weighing around 10 kilograms) in Low Earth Orbit (LEO) capable of colliding with intercontinental ballistic missiles during the boost-phase of their trajectory. These interceptors would remain in orbit for only 18 months. Brilliant Pebbles was cancelled in 1993 due to a lack of political support in Congress despite some strategists arguing the technical feasibility of the program and its technical readiness for deployment in the near term.
Since the program’s end, the technical efficiency of small pump-fed engines and the impulse of solid axial engines, the areas of technological development that limited the concept in the late 1980s, have improved. It is now possible for an interceptor to reach 20g acceleration and cover a range of 800 km, well beyond the capabilities in the original project. Further mission analysis is still needed to determine the number of Brilliant Pebbles required to provide adequate missile defenses within the Golden Dome strategy. Furthermore, the cost to deploy Brilliant Pebbles using this concept will also be vastly reduced using current U.S. space launch capabilities provides by companies such as SpaceX and Blue Origin.
The ability of Golden Dome to effectively protect the U.S. from air and space missile threats fundamentally relies on selecting the most effective space-based missile defense system. Brilliant Pebbles is a system whose maturity can be advanced quickly and cost effectively to provide a boost-phase intercept capability. This could finally put to an end to the “placebo” missile defense system which leaves the U.S. insufficiently defended.
Dr. Matthew Mowthorpe is currently working at BAE Systems where he is responsible for space control. Views expressed are the author’s own.
