On January 27, 2025, President Donald Trump issued an executive order that called for the creation of a missile defense shield protecting the United States that would, among other things, include boost-phase interceptors stationed in space. Critics of the administration’s intentions resurrect arguments first made in the 1980s: that a space-based missile defense would cost too much, wouldn’t work anyway, and would be destabilizing and undermine nuclear deterrence. While it would undoubtedly be technologically challenging and carry a hefty price tag, space-based missile defense is indeed worth serious consideration. These capabilities are likely to fit into a broader effort to revamp how the U.S. military uses space, recognizing that future wars will be fought from, through and in space.
The implications of space as a warfighting domain are still beginning to sink in. As they do, our evaluation of military capability in space will continue to mature. As it does, space-based missile defense capabilities will need to change as well. The advent of space fires is upon us. These will be kinetic and non-kinetic. They will include space to space fires, space to ground and, yes, space to missile fires. Space-based intercept is likely to emerge as a subset of a range of space fires. Assessing the capability must take place within that larger context.
Decades of history have passed
Unfortunately, discussion of the executive order has been largely mired in far too much ancient history. To be sure, space-based missile defenses were a key feature of President Ronald Reagan’s Strategic Defense Initiative (SDI), over four decades ago. Contemporary critics worried that SDI would create instability with the Soviet Union, undermining the concept of mutually assured destruction and threatening nuclear arms control agreements, as well as blame the U.S. for weaponizing space. Though the end of the Cold War put the last nail in SDI’s coffin, the program was saddled by the limitations of contemporary technology and high cost of space launch and finally cancelled in 1993.
One much-invoked 2004 study repeated many similar cost concerns. At the same time, critics continued to argue that pursuing space-based missile defense would accelerate the weaponization of space. A 2012 report reexamined space-based interceptors, warning that they could cost over $300 billion. Ironically, from 2002 to 2022, the Department of Defense would end up spending at least $174 billion on a different missile defense concept that targets missiles in their midcourse phase of flight, in many ways a far more difficult challenge than targeting a missile during its boost phase.
That was 20 years ago. Many of the assumptions baked into these prior assessments have changed due to tectonic geopolitical, strategic and technological shifts. Space access is far cheaper and satellites are manufactured at a scale exponentially greater than anything possible decades ago. Russia and China are busily weaponizing space to their advantage, in spite of U.S. calls for responsible behaviors in space. Meanwhile, hostile regimes, like Iran and North Korea, are developing better, longer-range missiles capable of striking the homeland.
In 1989, it cost about $30,000 per kilogram for launch into low Earth orbit. In 2018, it cost $1,500 per kilogram. That cost should drop to around $500 per kilogram in the coming years. Additionally, many companies have shown they can build and operate satellite constellations at scale. SpaceX alone can produce about five satellites per day and has thousands of satellites in orbit. Other companies are pursuing responsive space systems to put satellites into space on short notice, operating satellites at lower altitudes than had been the norm, and building capsules to survive atmospheric reentry — all three developments could support missile intercept systems. As launch costs plummet, the barriers to space fires do as well.
A new warfighting domain
Throughout the last few decades, ballistic missile threats to the U.S. and its allies have continued to grow. Both North Korea and Iran plod ahead on work to develop reliable, long range ballistic missiles. Concurrently, more countries and non-state actors, like the Houthis, have gained access to advanced missile technologies. China also continues efforts to develop a hypersonic glide vehicle (HGV) weapon launched on top of a ballistic missile. For a number of years, Russia too has focused on fielding an HGV launched by a long-range ballistic missile.
Space has become a place where wars will be fought, with U.S. military leaders emphasizing the need to protect and use space for operations. Though the U.S. has exercised a certain degree of restraint, limiting its use of debris-generating space weapons and focusing on responsible counterspace operations, China and Russia are aggressively using space for military operations and fielding more and more space weapon systems. Russia is even developing a new nuclear anti-satellite weapon. Meanwhile, Russia revised its nuclear doctrine, suggesting it would be more willing to use its weapons in a non-nuclear conflict, while China is expanding its own arsenal.
Ultimately, consideration of space-based missile defenses should be just one element of a broader reconsideration of the self-imposed restraints that the U.S. has placed on its military space power. Limiting counterspace operations to non-kinetic weapons, like electronic warfare and cyber, could leave military commanders without enough options to make the desired effects in space. Ignoring the potential of space-to-ground and space-to-air weapons misses a chance to develop entirely new ways to deliver firepower that could complement and back up traditional air power. Delivering munitions from space might be a way to bypass ever stronger integrated air defenses, which have proven effective in Ukraine and the Middle East, possibly foreshadowing what may play out in a future South China Sea conflict.
It is not 1984 or 2004 anymore. We are now in a new space age, and a new missile age. The significant level of technological change, the unalterable fact that space has shifted from a sanctuary to a warfighting domain today, and evolving missile and nuclear threat landscape calls for a reevaluation of the feasibility and desirability of a space-based missile defense layer. A sensible way to understand what’s within the realm of the possible for space-based missile defense, including costs, would be for the Pentagon to sketch out its requirements and ask industry for ideas. Ideally, such an initiative will be part of a larger plan taking into account the full warfighting potential of space, one that incorporates all elements of military space power to further U.S. national and economic security.
A new era of space fires is emerging, and space based intercept capability is likely to be part of it.
Clayton Swope is deputy director of the Aerospace Security Project and senior fellow of the Department of Security and Defense at the Center for Strategic and International Studies, Washington, D.C.
Tom Karako is director of the Missile Defense Project and senior fellow of the Department of Security and Defense at the Center for Strategic and International Studies.
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