Last week, President Donald Trump boasted of the inclusion of the “Golden Dome” missile defense program in the One Big Beautiful Bill Act, which the House narrowly passed Thursday. The funding, initially set at a staggering $175 billion, is for a long-standing Republican fantasy: total U.S. impunity to attacks from other nations.
“We will truly be completing the job that President Reagan started 40 years ago, forever ending the missile threat to the American homeland,” said Trump, flanked by posters showcasing the contiguous 48 states projected under a transparent golden force field. In fact, this technological promise is impossible to deliver, expensive to pursue, and one whose very development guides other nations into deadlier countermeasures that make America and the world less safe.
Missile defense on the scale of Golden Dome is especially confounded by the danger of a thermonuclear warhead.
Missiles — primarily intercontinental ballistic missiles — have posed a threat to the United States ever since the Soviet Union successfully tested its first ICBM in August 1957. The USSR launched Sputnik, the first human-made satellite, two months later, making it impossible for U.S. officials to hide the fact that the USSR had weapons which could hurl objects into the heavens and, far more ominously, send nuclear warheads crashing back down. Every president since Dwight Eisenhower has had to contend with the challenge of a nuclear-armed ICBM, fired far beyond the reach of U.S. forces and moving too fast to be intercepted by planes, destroying entire cities and ports.
The trajectory of an ICBM is a parabolic arc: The rocket launches upward toward space, then turns and arcs back down toward the Earth at tremendous speed, up to 15,000 mph. This downward trajectory and rapid descent mean any missile defense system must not only successfully track where the missile is in flight, but must accurately calculate where the missile is likely to be when an interceptor can reach it. An interception system built to stop ICBMs is likely to struggle with nuclear-armed cruise missiles, which fly at different speeds and trajectories than either submarine or land-based ballistic missiles.
The fear is compounded by the scale of nuclear arsenals. Russia maintains the world’s largest nuclear stockpile: about 870 nuclear warheads on ballistic missiles and 640 on submarine-launched missiles. The U.S. maintains 400 nuclear warheads on land-based intercontinental ballistic missiles, and roughly 970 are on submarine-launched ballistic missiles. Both arsenals also include hundreds of nuclear weapons that can be carried by bombers, including nuclear-tipped cruise missiles. And then there are other nuclear powers like China, whose arsenal, while still markedly smaller than that of the U.S. or Russia, is nevertheless growing.
The Jan. 27 executive order from the White House that set in motion the Golden Dome was called “The Iron Dome for America,” a reference to Iron Dome, the Israeli rocket interception that was first field tested in 2011 and has received funding from the United States ever since. Iron Dome pairs sensors with missile interceptors that allow it to track the trajectory of simple rockets — typically launched by groups like Hezbollah and Hamas — and then target interceptions with missiles. The sensors allow the system to discriminate between rockets that are likely to hit buildings and ones that will miss and thus don’t require interception.
But Iron Dome’s task is easier than what Golden Dome would face, as Iron Dome usually faces cheap rockets with simple trajectories and only small, conventional payloads. Even with that success, Iron Dome is an expensive tool for the targets it intercepts. The rockets it typically intercepts cost hundreds of dollars, while the interceptors it fires cost tens of thousands.
Developing missile defense is expensive, and the United States has already appropriated $250 billion since 1985 attempting to make it work.
Other kinds of battlefield missile defense, designed for everything from rockets to conventional missiles, have been used by Israel, the United States and other countries, like Saudi Arabia (against the Houthis) or Ukraine (against Russia). The continental United States does not face conventional missile threats from nearby enemies, and it would take a catastrophic turn in Mexican- or Canadian-U.S. relations for that to change.
Missile defense on the scale of Golden Dome is especially confounded by the danger of a thermonuclear warhead, where even one warhead reaching ground can result in tens of thousands of deaths. The only nuclear weapons used so far in war, the fission bombs the United States dropped on Hiroshima and Nagasaki, killed an estimated 110,000 to 210,000 people.
Modern warheads are typically at least one order of magnitude more powerful, and since the 1960s, nuclear weapon development has included missiles with multiple independently targetable re-entry vehicles, warheads that can ride one missile to space and then go in different directions upon the return to Earth. Missiles can also release decoys, which only have to fool missile defense long enough for an interceptor to miss.
An attacker can also build more weapons. ICBMs are expensive, but the rocketry is largely 1960s and 1970s technology, even as designs have been iterated on since. During the nuclear arms race of the Cold War, the United States and the USSR built staggeringly large arsenals that could overwhelm attempts at missile defense.
We have already seen one country try to overwhelm the missile defenses of another. In April and October of 2024, Iran launched retaliatory missile attacks against Israel for, respectively, an attack on an Iranian Embassy in Syria and the assassination in Iran of a Hamas leader. The April attack involved 120 ballistic missiles, and the October attack 180, the increase in the latter seen as an attempt to overwhelm defenses through heavy saturation. After the attack, Israel claimed that it had intercepted the majority of attacks, while Iran claimed a 90% success rate.
If missile defense works as promised, it creates an opportunity for the leadership of the protected country to launch nuclear strikes without fear of suffering nuclear retaliation in return. This is true even if missile defense does not actually work as a defense, because overcoming planned defenses means building a larger arsenal and possibly taking a gamble on launching a nuclear first strike, rather than forever losing that deterrent effect.
Developing missile defense is expensive, and the United States has already appropriated $250 billion since 1985 attempting to make it work. Interception is harder than launching a missile: It requires an array of sensors to track the incoming threat and then infer the intercept trajectory, and often requires firing two or more interceptors per incoming missile. The cost of a successful interception is the full expense of developing the system, the interceptors, coordinating the sensors, and maintaining the defenses through constant upgrades to stay ahead of what is almost invariably an increasing arsenal to defend against.
What compounds these dangers is the possibility that missile defense is pursued despite these calculations, and then the results are staged and yet presented as a success. This isn’t speculation; this actually happened with “Star Wars,” Ronald Reagan’s missile defense initiative.
“Officials in the ‘Star Wars’ project rigged a crucial 1984 test and faked other data in a program of deception that misled Congress as well as the intended target, the Soviet Union,” four former Reagan administration officials told The New York Times in 1993. The rigging was apparently designed to spur Soviet expenditures countering missile defense, a dangerous gamble on all counts. If the USSR believed the system was likely to work, Soviet leaders may have more readily risked a pre-emptive strike. And if American presidents were told the system was a success, they might have been more willing to escalate, rather than back down, in a conflict, overconfident in the protection of a shield that functionally doesn’t exist.
The physics and engineering challenges of missile defense are real and hard, and it comes with a promise of safety on the other end. But the designers of defensive weapons are not the only ones who get a say in offense-defense development, and nuclear warheads make the stakes of failure that much greater. Pursuing Golden Dome makes the U.S. less safe, and for all the victories of systems like Iron Dome, none have reckoned with nuclear threats or interception-defeat tools. To borrow a phrase, missile defenses have to get lucky every time; nuclear weapons only have to get lucky once.