Why Some Experts Call Trump’s ‘Golden Dome’ Missile Shield a Dangerous Fantasy
The White House’s $175-billion plan to protect the U.S. from nuclear annihilation will probably cost much more—and deliver far less—than has been claimed, says nuclear arms expert Jeffrey Lewis
U.S. President Donald Trump speaks in the Oval Office of the White House on May 20, 2025, during a briefing announcing his administration’s plan for the “Golden Dome” missile defense shield.
During a briefing from the Oval Office this week, President Donald Trump revealed his administration’s plan for “Golden Dome”—an ambitious high-tech system meant to shield the U.S. from ballistic, cruise and hypersonic missile attacks launched by foreign adversaries. Flanked by senior officials, including Secretary of Defense Pete Hegseth and the project’s newly selected leader, Gen. Michael Guetlein of the U.S. Space Force, Trump announced that Golden Dome will be completed within three years at a cost of $175 billion.
The program, which was among Trump’s campaign promises, derives its name from the Iron Dome missile defense system of Israel—a nation that’s geographically 400 times smaller than the U.S. Protecting the vastness of the U.S. demands very different capabilities than those of Iron Dome, which has successfully shot down rockets and missiles using ground-based interceptors. Most notably, Trump’s Golden Dome would need to expand into space—making it a successor to the Strategic Defense Initiative (SDI) pursued by the Reagan administration in the 1980s. Better known by the mocking nickname “Star Wars,” SDI sought to neutralize the threat from the Soviet Union’s nuclear-warhead-tipped intercontinental ballistic missiles by using space-based interceptors that could shoot them down midflight. But fearsome technical challenges kept SDI from getting anywhere close to that goal, despite tens of billions of dollars of federal expenditures.
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To get a better sense of what’s at stake—and whether Golden Dome has a better chance of success than its failed forebears—Scientific American spoke with Jeffrey Lewis, an expert on the geopolitics of nuclear weaponry at the James Martin Center for Nonproliferation Studies at the Middlebury Institute of International Studies.
[An edited transcript of the interview follows.]
It’s been a while, but when last I checked, most experts considered this sort of plan a nonstarter because the U.S. is simply too big of a target. Has something changed?
Well, yes and no. The killer argument against space-based interceptors in the 1980s was that it would take thousands of them, and there was just no way to put up that many satellites. Today that’s no longer true. SpaceX alone has put up more than 7,000 Starlink satellites. Launch costs are much cheaper now, and there are more launch vehicles available. So, for the first time, you can say, “Oh, well, I could have a 7,000-satellite constellation. Do I want to do that?” Whereas, when the Reagan administration was talking about this, it was just la-la land.
But let’s be clear: this does not solve all the other problems with the general idea—or the Golden Dome version in particular.
What are some of those other problems?
Just talking about space-based interceptors, there are a couple [of issues that] my colleagues and I have pointed out. We ran some numbers using the old SDI-era calculation from [SDI physicists] Ed Teller and Greg Canavan—so we couldn’t be accused of using some hippie version of the calculation, right? And what this and other independent assessments show is that the number of interceptors you need is super-duper sensitive to lots of things. For instance, it’s not like this is a “one satellite to one missile” situation—because the physics demands that these satellites … have to be in low-Earth orbit, and that means they’re going to be constantly moving over different parts of the planet.
So if you want to defend against just one missile, you still need a whole constellation. And if you want to defend against two missiles, then you basically need twice as many interceptors, and so on.
Let’s get back to the sheer physics-induced numbers for a moment, which AI can’t really do much about. That daunting scaling I mentioned also depends on the quality of your interceptors, your kill vehicles—which, by the way, are still going to be grotesquely expensive even if launch costs are low. If your interceptors can rapidly accelerate to eight or 10 kilometers per second (km/s), your constellation can be smaller. If they only reach 4 km/s, your constellation has to be huge.
The point is: any claim that you can do this with relatively low numbers—let’s say 2,000 interceptors—assumes a series of improbable miracles occurring in quick succession to deliver the very best outcome that could possibly happen. So it’s not going to happen that way, even if, in principle, it could.
So you’re telling me there’s a chance! No, seriously, I see what you mean. The arguments in favor of this working seem rather contrived. No system is perfect, and just one missile getting through can still have catastrophic results. And we haven’t even talked about adversarial countermeasures yet.
There’s a joke that’s sometimes made about this: “We play chess, and they don’t move their pieces.” That seems to be the operative assumption here: that other nations will sit idly by as we build a complex, vulnerable system to nullify any strategic nuclear capability they have. And of course, it’s not valid at all. Why do you think the Chinese are building massive fields of missile silos? It’s to counteract or overwhelm this sort of thing. Why do you think the Russians are making moves to put a nuclear weapon in orbit? It’s to mass kill any satellite constellation that would shoot down their missiles.
Golden Dome proponents may say, “Oh, we’ll shoot that down, too, before it goes off.” Well, good luck. You put a high-yield nuclear weapon on a booster, and the split second it gets above the clouds, sure, you might see it—but now it sees you, too, before you can shoot. All it has to do at that point is detonate to blow a giant hole in your defenses, and that’s game over. And by the way, this rosy scenario assumes your adversaries don’t interfere with all your satellites passing over their territory in peacetime. We know that won’t be the case—they’ll light them up with sensor-dazzling lasers, at minimum!
You’ve compared any feasible space-based system to Starlink and noted that, similar to Starlink, these interceptors will need to be in low-Earth orbit. That means their orbits will rapidly decay from atmospheric drag, so just like Starlink’s satellites, they’d need to be constantly replaced, too, right?
Ha, yes, that’s right. With Starlink, you’re looking at a three-to-five-year life cycle, which means annually replacing one third to one fifth of a constellation.So let’s say Golden Dome is 10,000 satellites; this would mean the best-case scenario is that you’re replacing 2,000 per year. Now, let’s just go along with what the Trump administration is saying, that they can get these things really cheap. I’m going to guess a “really cheap” mass-produced kill vehicle would still run you $20 million a pop, easily. Just multiply $20 million by 2,000, and your answer is $40 billion. So under these assumptions, we’d be spending $40 billion per year just to maintain the constellation. That’s not even factoring in operations.
And that’s not to mention associated indirect costs from potentially nasty effects on the upper atmosphere and the orbital environment from all the launches and reentries.
That, yes—among many other costly things.
I have to ask: If fundamental physics makes this extremely expensive idea blatantly incapable of delivering on its promises, what’s really going on when the U.S. president and the secretary of defense announce their intention to pump $175 billion into it for a three-year crash program? Some critics claim this kind of thing is really about transferring taxpayer dollars to a few big aerospace companies and other defense contractors.
Well, I wouldn’t say it’s quite that simple.
Ballistic missile defense is incredibly appealing to some people for reasons besides money. In technical terms, it’s an elegant solution to the problem of nuclear annihilation—even though it’s not really feasible. For some people, it’s just cool, right? And at a deeper level, many people just don’t like the concept of deterrence—mutual assured destruction and all that—because, remember, the status quo is this: If Russia launches 1,000 nuclear weapons at us—or 100 or 10 or even just one—then we are going to murder every single person in Russia with an immediate nuclear counterattack. That’s how deterrence works. We’re not going to wait for those missiles to land so we can count up our dead to calibrate a more nuanced response. That’s official U.S. policy, and I don’t think anyone wants it to be this way forever. But it’s arguably what’s prevented any nuclear exchange from occurring to date.
You’re saying this isn’t about money?
Well, I imagine this is going to be good for at least a couple of SpaceX Falcon Heavy or Starship launches per year for Elon Musk. And you don’t have to do too many of those launches for the value proposition to work out: You build and run Starlink, you put up another constellation of space-based missile defense interceptors, and suddenly you’ve got a viable business model for these fancy huge rockets that can also take you to Mars, right?
Given your knowledge of science history—of how dispassionate physics keeps showing space-based ballistic missile defense is essentially unworkable, yet the idea just keeps coming back—how does this latest resurgence make you feel?
When I was younger, I would have been frustrated, but now I just accept human beings don’t learn. We make the same mistakes over and over again. You have to laugh at human folly because I do think most of these people are sincere, you know. They’re trying to get rich, sure, but they’re also trying to protect the country, and they’re doing it through ways they think about the world—which admittedly are stupid. But, hey, they’re trying. It’s very disappointing, but if you just laugh at them, they’re quite amusing.
I think most people would have trouble laughing about something as devastating as nuclear war—or about an ultraexpensive plan to protect against it that’s doomed to failure and could spark a new arms race.
I guess if you’re looking for a hopeful thought, it’s that we’ve tried this before, and it didn’t really work, and that’s likely to happen again.
So how do you think it will actually play out this time around?
I think this will be a gigantic waste of money that collapses under its own weight.
They’ll put up a couple of interceptors, and they’ll test those against a boosting ballistic missile, and they’ll eventually get a hit. And they’ll use that to justify putting up more, and they’ll probably even manage to make a thin constellation—with the downside, of course, being that the Russians and the Chinese and the North Koreans and everybody else will make corresponding investments in ways to kill this system.
And then it will start to really feel expensive, in part because it will be complicating and compromising things like Starlink and other commercial satellite constellations—which, I’d like to point out, are almost certainly uninsured in orbit because you can’t insure against acts of war. So think about that: if the Russians or anyone else detonate a nuclear weapon in orbit because of something like Golden Dome, Elon Musk’s entire constellation is dead, and he’s probably just out the cash.
The fact is: these days we rely on space-based assets much more than most people realize, yet Earth orbit is such a fragile environment that we could muck it up in many different ways that carry really nasty long-term consequences. I worry about that a lot. Space used to be a benign environment, even throughout the entire cold war, but having an arms race there will make it malign. So Golden Dome is probably going to make everyone’s life a little bit more dangerous—at least until we, hopefully, come to our senses and decide to try something different.
Lee Billings is a science journalist specializing in astronomy, physics, planetary science, and spaceflight, and is a senior editor at Scientific American. He is the author of a critically acclaimed book, Five Billion Years of Solitude: the Search for Life Among the Stars, which in 2014 won a Science Communication Award from the American Institute of Physics. In addition to his work for Scientific American, Billings’s writing has appeared in the New York Times, the Wall Street Journal, the Boston Globe, Wired, New Scientist, Popular Science, and many other publications.
Billings joined Scientific American in 2014, and previously worked as a staff editor at SEED magazine. He holds a B.A. in journalism from the University of Minnesota.
Source: www.scientificamerican.com