In January President Donald Trump made a bold pronouncement, calling for colossal investment in a missile defense shield called Iron Dome for America, later renamed the Golden Dome for America. It would coordinate missile interceptors that could be fired from the ground or from space, as well as radar arrays, lasers, electronic weapons and networks of sensor-equipped satellites. Meant to shield the entire continental U.S. at minimum, it would be vastly larger in scale and sophistication than current, largely U.S.-designed missile defense systems in places such as Israel, South Korea and Eastern Europe.
If this weren’t bold enough, Trump upped the ante during a White House press conference in May, proclaiming that Golden Dome would be fully operational by the end of his term for a total cost of $175 billion. The race to meet that looming deadline truly began in July, when Congress appropriated a down payment of $25 billion for the initiative. Officials from the Department of Defense—now being renamed the Department of War—have subsequently said the first major test of Golden Dome is targeted for the fourth quarter of 2028, just before the next presidential election.
Yet several months and billions of dollars later, few further details have been released about the project’s scope and logistics. So many major unknowns remain that unease about the program is mounting among many policymakers, missile defense experts and geopolitical analysts. Why, they wonder, is there such a rush to proceed when the plan itself remains so nebulous? How can its feasibility and risks be properly evaluated without a clearer picture of what exactly is even being considered or pursued? Is Golden Dome destined to be a critical pillar of U.S. defense—or a multibillion-dollar boondoggle better at lining the pockets of Trump administration allies than at shooting down any missiles?
On supporting science journalism
If you’re enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today.
An early-August expert gathering in Huntsville, Ala.—the annual Space and Missile Defense Symposium—offered a valuable opportunity to discuss Golden Dome and address such questions. Secretary of Defense Pete Hegseth prohibited participating officials from talking about it there, however. In addition, media were barred from attending a separate Golden Dome industry summit event in Huntsville that was hosted by the Pentagon’s Missile Defense Agency (MDA).
David Wright, a Massachusetts Institute of Technology physicist and arms control expert, views this ongoing lack of transparency as one of many ominous warning signs. “The Pentagon has done several things recently to decrease oversight of this system,” he says. He cites Hegseth’s gutting of the office that would have overseen Golden Dome testing, as well as the program’s exemption from usual “fly before you buy” rules meant to minimize spending on pie-in-the-sky acquisitions. Without those guardrails, Wright says, “you can end up wasting a lot of money by building stuff that doesn’t work.”
The technical challenge of shooting down just one intercontinental ballistic missile (ICBM) is extreme, often compared with hitting a bullet with a bullet.
In the 1980s then president Ronald Reagan established the Strategic Defense Initiative (SDI)—more commonly called the “Star Wars” program—to do just that at unprecedented scales. SDI envisioned deploying space-based interceptors and directed energy weapons to defend the U.S. against nuclear annihilation by barrages of Soviet ICBMs. But Reagan’s ambitious initiative was panned by critics as ruinously expensive and fundamentally unworkable. It fizzled out soon after the cold war ended, although the Pentagon has maintained more modest multibillion-dollar missile defense programs ever since.
On September 3 of this year, Senator Ed Markey of Massachusetts criticized Trump’s claim that he would be “completing the job” that Reagan started. Instead, Markey said on the Senate floor, “what it will really do is bury arms control, balloon the deficit, and boost the bottom lines of billionaires.” He also said the government owes it to taxpayers “to have a plan, to know how much it will cost and to ensure that it will work.” On the other side, congressional proponents such as Representative Dale Strong of Alabama formed a Golden Dome caucus to advance the project. “With nuclear-capable adversaries across the globe, we can’t afford for this vision to not become a reality,” Strong said in a statement in June.
The physics of missile defense haven’t changed since SDI’s demise—but the world has, along with its arsenals. Where once strategic bombardment by Russian nukes was the primary concern, now a robust defense must account for many additional possible adversaries and scenarios—long-range missiles from China or North Korea, midrange strikes by Iran on U.S. assets throughout the Middle East and the possibility of unconventional drone attacks from state and nonstate actors across the globe.
Missile defense technology has changed, too, becoming more advanced and effective. “Hit-to-kill technology has gotten good enough that you can hit a bullet with a bullet, under good circumstances, a pretty high percentage of the time,” Wright says. The interceptors of Israel’s Iron Dome, for instance, reportedly stopped some 85 percent of ballistic missiles and drones launched in retaliatory strikes by Iran during a conflict between those nations in June.
That hit rate is technologically impressive, but as Wright argued in a recent paper, it’s unlikely to translate into success for Golden Dome. In those June exchanges, Iron Dome was defending a small area, about the size of New Jersey, against a lone adversary’s conventional medium-range missiles that deployed few, if any, meaningful countermeasures. This is a far cry from Golden Dome’s much more difficult general goal of defending the U.S. homeland from all manners of missiles from a multitude of nations, including ones carrying nuclear warheads and augmented by any number of sophisticated countermeasures, such as radar jammers, missile-mimicking decoys and clouds of ejected chaff.
Interceptors from Israel’s Iron Dome system streak through the skies to defend against a barrage of ballistic missiles launched by Iran on June 21, 2025.
Eli Basri/SOPA Images/LightRocket via Getty Images
Potentially adding to the difficulty, in August Canada agreed to join Golden Dome, further expanding the territory intended to fall under the system’s protection. Golden Dome’s scope also may or may not include Alaska and Hawaii, as well as Guam and various international sites hosting U.S. military facilities. Beyond these myriad uncertainties, Pentagon officials also have not revealed the “effectiveness” they intend to achieve, referring to the fraction of incoming missiles Golden Dome would be designed to intercept.
While details may be lacking, the MDA has outlined broad contours of a multilayer design for Golden Dome, according to slides reportedly entitled “Go Fast, Think Big!” that were presented at the Huntsville industry summit. The design includes a space layer, existing regional missile defense systems (such as Terminal High Altitude Area Defense, or THAAD) and defense focused on high-value locations, and all of these components have to be somehow integrated with each other.
“You’re not going to have one capability that can mitigate all the threats,” says Clayton Swope, deputy director of the Aerospace Security Project at the Center for Strategic & International Studies, which receives some funding from Lockheed Martin and other potential contractors. But fundamentally it remains unclear what form Golden Dome will take, he says. “Until we answer that question, a lot of the pros and cons can’t really be debated, including ‘Is it worth it?’”
Space-based interceptors don’t exist yet, but it’s possible to deploy satellites into low-Earth orbit that could launch their own quickly maneuvering projectiles into the path of an incoming missile, ram into it and damage or destroy it, says Laura Grego, a security and space policy expert at the Union of Concerned Scientists. Beyond those, most of the technologies that could be notional components of Golden Dome are already available. In theory, the missile defense system’s layers would complement one another, for example, against an incoming ICBM: one type of interceptor could target it during the boost phase, when the missile would be rising after takeoff; others could take aim during the midcourse phase; and others could do so during the terminal phase, as the missile descended toward its target.
Researchers have studied missile defense for decades. According to a 2012 report from the National Academies of Sciences, Engineering, and Medicine, the components of the current midcourse missile defense system—including antiballistic interceptors based in Alaska and California—“have shortcomings that limit their effectiveness against even modestly improved threats,” and the system is “deficient with respect to all” fundamental principles of a cost-effective defense. Additionally, a critical American Physical Society report released in March 2025 pointed out that boost-phase missile defense is thwarted if an ICBM isn’t detected with confidence within 45 seconds or if its trajectory is not well understood within another 20 seconds. There is little room for error.
Nevertheless, what’s challenging isn’t the tech but the economics, Grego says, because it’s relatively easy for attackers to evade or overwhelm the defense.
Fielding more ICBMs or augmenting them with countermeasures, for example, is cheap compared with the cost of building any conceivable missile defense system. To protect against one or two slow-moving ICBMs, which could launch from many different sites, hundreds of interceptors would be needed; for fast-moving missiles, thousands would be required to ensure a high chance of interception. And similar to the Starlink satellite constellations that provide lightning-fast global broadband Internet coverage, Golden Dome’s fleet of interceptors in low-Earth orbit would gradually decay without regular (and expensive) replenishment as atmospheric drag pulled individual spacecraft back down to fiery reentries.
This all but guarantees that space-based missile defense would be Golden Dome’s most expensive layer by far, potentially costing more than $1 trillion, according to that 2012 report.
For its part, a report released in May by the Congressional Budget Office calculated $831 billion as a high estimate for the total cost of Golden Dome’s interceptor constellation over 20 years. The cost of launching numerous spacecraft could decline by some 30 percent in the coming years, the report stated, thanks to innovations from companies such as SpaceX, Rocket Lab and Blue Origin. But experts caution such market trends probably won’t translate into a significantly cheaper Golden Dome. “Take that [30 percent figure] with a grain of salt. The government is not seeing this big decrease in launch costs,” says Bonnie Triezenberg, a senior engineer at the nonprofit think tank RAND, which receives some of its funding from defense and national security agencies.
Irrespective of cost, any space-based system would also be very vulnerable to counterattack, Grego points out, with each compromised spacecraft creating a gap in the missile-defense satellite constellation; only one nuclear-tipped missile slipping through to strike its target would be enough to cause catastrophe. “In the rush to raise their hands and say, ‘I’ll help build this,’ no one’s requiring an answer to those basic questions: How do you keep it safe? How do you make it economical?”
It’s not just the Pentagon looking to late 2028 as a make-or-break moment for Golden Dome; the U.S. aerospace industry is as well. Lockheed Martin is targeting that year for a demonstration of a space-based interceptor for the system, although no commercial contracts have yet been inked. Other defense contractors seek to join the project as well: Northrop Grumman is expanding its missile defense production capacity in Alabama—near Huntsville, the relocated headquarters of U.S. Space Command—and L3Harris is expanding its satellite integration and test facility in Florida. Raytheon, Boeing and Leidos are all gearing up for potential high-dollar contracts, too.
Some experts, such as Victoria Samson of the Secure World Foundation, are skeptical of these deadlines. After all, during President Trump’s first term, his administration set the Artemis moon program in motion and planned to land a crew on the moon by 2024. That mission is still years away, and the program’s future is uncertain.
On July 22 Space Force General Michael Guetlein, head of Golden Dome, stated that he had a 60-day deadline to present an “architecture” for the program. Samson, Triezenberg and other experts don’t expect such a blueprint to actually present many new details, and it may merely involve current missile defense systems.
Grego raises an additional concern: even if Golden Dome’s space-based interceptors can’t neutralize the threat of ICBMs, they can still do much more than shoot down missiles. Interceptors can be used, for instance, to target rivals’ spacecraft, leading to a strategically destabilizing “more overt weaponization of space, which becomes extremely dangerous,” she says.
Facing an escalating orbital arms race, adversaries could seek to reset the balance of power by eliminating interceptors and other space-based assets en masse—something most effectively done via a nuclear detonation in space. Given that the sole remaining nuclear treaty between the U.S. and Russia is set to expire in February 2026 and that space weaponry is scarcely mentioned in current arms control accords, any missile-defense orbital armada could also constitute a flash point for global thermonuclear war.
The threadbare status of international arms control agreements may be one reason for the U.S. government’s increasing investment in missile defense, Wright says. “When politicians get asked what they’re going to do about the threat, if you’re not doing arms control and you don’t know what else you could do, the easiest thing to say is ‘We’re going to spend money on defense.’”
A different question entirely is whether the American public would actually be well served by a missile defense initiative that could potentially consume more than $1 trillion of taxpayer money and result in the militarization of low-Earth orbit. As long as the Trump administration remains nebulous about the plan and its true cost, its clearest outcome may well be the perilous acceleration of arms races and the enrichment of profit-seeking defense and space-tech contractors for what is, at best, only the illusion of safety.
