This article is published in Aviation Week & Space Technology and is free to read until Mar 07, 2025. If you want to read more articles from this publication, please click the link to subscribe.

Northrop Grumman’s Glide-Phase Interceptor is intended to focus on hypersonic threats, as President Trump is calling on the Pentagon to work on an architecture that focuses on all missile threats.
President Donald Trump’s first major defense modernization initiative since returning to the White House evokes the height of the Cold War in the early 1980s. His plan calls for the creation of a massive missile defense system centered on the tenets of the Reagan administration’s “Star Wars” bolstered by advances in technology and space launch.
Outlined in an executive order titled “The Iron Dome for America,” the approach would be a major step in missile defense if realized. Experts say the initiative is coupled with uncertainty, primarily about funding and aspirations to shift away from deterrence toward active defense both on the ground and in space.
- The plan includes a new ground-based underlayer
- Acquisition changes will be needed, experts assert
While the executive order uses the official name, Rafael’s Iron Dome—the short-range system that protects Israel from relatively simple threats, such as unguided rockets and mortars—the multiprong presidential directive is anything but simple and short-range.
The order calls on the Defense Department to submit a report within 60 days outlining the reference architecture, requirements and implementation plan for a broad next-generation missile defense shield focused on ballistic, hypersonic, advanced cruise missiles and other aerial attacks. Along with accelerating existing programs, such as the Missile Defense Agency’s (MDA) Hypersonic and Ballistic Tracking Space Sensor layer and the Space Development Agency’s (SDA) Proliferated Warfighter Space Architecture, the two major efforts of the order focus on creating a new “underlayer” to protect the nation and developing boost-phase interceptors that are based in space.
That last directive hearkens back to the Reagan administration’s original Strategic Defense Initiative (SDI), consisting of space- and ground-based sensors and interceptors. Some, including the Ground-Based Interceptor and Northrop Grumman’s Space Tracking and Surveillance System, eventually entered service. The Brilliant Pebbles ballistic missile defense system, proposed by a scientist at Lawrence Livermore National Laboratory, emerged from the SDI and focused on a proliferated architecture of small satellites outfitted with missiles to take down Soviet ICBMs.
After the fall of the Soviet Union, then-President Bill Clinton canceled Brilliant Pebbles in 1993, but the feasibility of such a system has remained an open question. A jointly funded lunar exploration mission by NASA and the Strategic Defense Initiative Organization proved in 1994 that the targeting sensors planned for the Brilliant Pebbles interceptors worked. Each interceptor was designed to be small and relatively inexpensive, but the price to launch about 1,000 of them into low Earth orbit (LEO) seemed high. Although the 1972 Anti-Ballistic Missile Treaty directly barred space-based interceptors, in 2001, then-President George W. Bush withdrew from the treaty, allowing another attempt to field a defensive shield in space against long-range missile attacks.
With the expansion of private space launch companies, notably SpaceX, and increased focus on proliferated LEO architectures under such organizations as the SDA, the cost of launch could be less of a concern. For example, it cost approximately $22,200 per kilogram in today’s dollars to send a payload to space on an Atlas II rocket, which was in service when Brilliant Pebbles was canceled. Today, a SpaceX Falcon Heavy can loft a payload into space for as little as $1,700 per kilogram.
The steep reduction in space launch costs is not the only obstacle, however. A constellation of space-based interceptors moving in low Earth orbit scales poorly with missile threats, says Todd Harrison, a senior fellow at the American Enterprise Institute.
It takes a constellation of 1,900 interceptors in space to shoot down two long-range ballistic missiles launched simultaneously, Harrison says. About 3,800 space-based interceptors are necessary to defend against a salvo of four missiles.
“The space-based part of this [concept], I think it is not that useful or helpful in the end,” Harrison adds.
The order also calls on the SDA to begin work on a custody layer as part of its Proliferated Warfighter Space Architecture, something the U.S. Space Force has been reticent to take on amid disputes with the National Reconnaissance Office and the National Geospatial-Intelligence Agency, Harrison says. “It looks like Trump is going to finally break that impasse and let the Space Force start work on this important capability,” he says.
The SDA is fielding hundreds of LEO-based satellites into one constellation enabling global communications, missile warning and tracking, battlespace awareness and alternate navigation. The agency aims to incorporate remote-sensing spacecraft eventually to support niche missions as part of a planned custody layer, although the fielding timeline is budget-dependent, according to the SDA.
The SDA also is developing a series of prototype spacecraft meant to prove out new capabilities on orbit, such as the FOO Fighter (Fire-Control On-Orbit Support to the Warfighter) effort to showcase advanced fire control. Boeing subsidiary Millennium Space Systems is building eight satellites for the program, due to launch in 2027. FOO Fighter aims to help demonstrate capabilities that could be fielded operationally as part of the custody layer before new dedicated satellites are folded into future tranches, then-SDA Director Derek Tournear told Aviation Week in September.
In highlighting the MDA’s Hypersonic and Ballistic Tracking Space Sensor, the executive order appears to prefer that effort over the SDA’s similar Tracking Layer. The MDA’s effort uses a more sensitive infrared sensor with a medium field of view, as opposed to the SDA’s wide-field-of-view sensor.
Experts say the proposed underlayer of protection on the ground could close glaring gaps in current systems—depending on whether the identified threat is an ICBM or something smaller like a cruise missile or UAV. That will “completely affect what you do,” says Tom Karako, director of the Missile Defense Project and senior fellow at the Center for Strategic and International Studies.
Historically, the underlayer has focused on ICBM defense. Under the first Trump administration, there was a push to shift Raytheon SM-3 IIA exo-atmospheric missile defense interceptors toward homeland defense. Karako says this “didn’t go very far,” but the threat has advanced since the first Trump term, and he notes that there could be “some muscle memory there” to use the interceptor along with Lockheed Martin Terminal High-Altitude Area Defense (THAAD) systems to underlie the Ground-Based Midcourse Defense system.
The order calls for the underlayer and terminal-phase interceptors to defeat “countervalue attacks,” a term used for nuclear strikes on nonmilitary targets, such as cities and civilian populations.
Karako says the foundation of an “Iron Dome for America” should be air and cruise missile defense, which could plausibly be done with Patriot and National Advanced Surface-to-Air Missile Systems, possibly augmented by the U.S. Army’s Indirect Fire Production Capability-Increment 2. Of course, all of this is a guess ahead of the Pentagon’s report in response to the executive order, Karako says. “We don’t know yet. If someone tells you they do, they don’t.”
One key change needed to improve air and missile defense on this scale is to acquisition authority. The MDA’s charter was last formally modified in 2014, and an update is in the works to speed its procurement of systems, akin to how military services work with groups such as the Air Force’s Rapid Capabilities Office. It is an open question if the new charter will be sufficient to the task at hand, Karako says.
In the interim, the U.S. military can pull some deployed Patriot and THAAD systems from forward bases to bolster homeland defense, asserts Riki Ellison, founder and chairman of the Missile Defense Advocacy Alliance. He says that although the services will put up a “big-time” fight against the change, substantial gaps must be filled. Aegis ships can be parked off the U.S. coast coupled with vertical launch systems on the ground, he notes.
Ellison says beyond the executive order, there needs to be a presidential directive to create momentum to make the plan real— something similar to what Bush did in 2002 to start the process of fielding Ground-Based Interceptors to counter threats from rogue states. Ellison estimates the effort would cost $20-50 billion and take “a lot more than four years.” However, he says investment like this coupled with a presidential directive is needed because the threats are not the same as they were under Bush’s directive.
“It is a striking way to regain deterrence that was lost,” Ellison says. “It’s a very bold initiative. If implemented, it will do what Reagan asked to do in ’83, what George Bush tried to do [in 2002].
“It’s the end of an era of arms control, an era that lasted a long time,” he says. “Arms control is not in this debate anymore.”
—With Steve Trimble in Washington and
Vivienne Machi in Orlando, Florida
Editor’s Note: This story has been updated to reflect new comments by Todd Harrison about the feasibility of space-based interceptors.
Comments