On 20 May 2025, Donald Trump announced one of the most ambitious and controversial defence initiatives in US history: the Golden Dome.
The proposed $175 billion programme, which Trump wants completed before the end of his term in January 2029, aims to create an all-encompassing missile shield to protect the US from nuclear threats, including intercontinental ballistic missiles (ICBMs) and hypersonic weapons.
Drawing inspiration from Israel's Iron Dome, the plan envisions a global network of ground- and space-based detectors and interceptors that could knock enemy missiles out of the sky before they reach the US.
The administration has yet to spell out exactly how this would work – but critics say the idea is not only unrealistic, but potentially dangerous and destabilising.
A red line for space
“Golden Dome is like a Strategic Defence Initiative redo,” Dr Michael Mulvihill, vice chancellor research fellow at Teesside University and an expert in the geopolitical and technological consequences of space weaponisation, tells BBC Science Focus. “There’s an awful lot of political theatre about it.”
The Strategic Defense Initiative – or SDI – was a proposed US missile defence system championed by President Ronald Reagan in the 1980s. Dubbed 'Star Wars' by critics, it aimed to use lasers, satellites and other space-based technologies to shoot down incoming Soviet missiles. The project was ultimately shelved, seen as technologically unfeasible and prohibitively expensive.
Golden Dome, Mulvihill argues, risks reviving the same flawed thinking, with even greater consequences for the security of space.
While space has long supported military operations through satellite tracking, communications and navigation, it has never been an overt warfighting domain. In fact, agreements such as the Outer Space Treaty expressly prohibit the use of space for non-peaceful purposes.
Golden Dome could change that.
“This could be a starting gun – a catalyst to start weaponising space and deploying all sorts of systems that have been developed over the past few years,” Mulvihill says.
He adds the concern is not just about the US deploying weapons in orbit, but what happens next: "If the US gets a Golden Dome, China will want one too… It’s got capabilities to be able to do it.”
Throw in other space-faring nations like Russia, and the risks of a full-blown orbital arms race could start to look very real.
Fuel for proliferation
Critics such as Mulvihill warn that a space-based missile shield might backfire, making the world less secure rather than more. The reasoning is simple: if one side develops a defence system that can shoot down incoming missiles, the other side may respond by building even more missiles to overwhelm it.
"This has always been the problem with anti-ballistic missile systems," says Mulvihill. "You can overload them. That’s what happened in the 1960s and 70s. The US and USSR just added more warheads. You end up with more missiles, not fewer."
Every defence system has a limit. And if the Cold War taught us anything, it’s that superpowers will build as many warheads as it takes to ensure at least one gets through.
Golden Dome, Mulvihill argues, risks repeating that cycle on an even larger scale.
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Low Earth orbit is already crowded
Golden Dome would also require thousands of new satellites. Its space-based component may involve a Starlink-style mega-constellation armed with interceptor missiles to target ICBMs in their boost phase – that is, within the first few minutes of launch.
That’s not just ambitious; it’s dangerous.
According to a 2024 study in Nature Sustainability, the number of satellites in low Earth orbit (LEO) is on track to exceed 100,000 by 2034. NASA estimates there are already over 25,000 pieces of debris larger than 10cm, and around 500,000 smaller fragments.
Even without weapons, space is becoming harder to navigate. Add thousands of military satellites, and you increase the risk of collisions and debris significantly.
"If one of those interceptors gets hit or explodes, it’s not just one satellite that’s lost. You could close off entire orbits for years," Mulvihill says.
He offers a grim analogy: "In naval warfare, if a ship sinks, it leaves the battlefield. In space, the wreckage stays up there, circling the Earth at thousands of kilometres per hour."
Is Golden Dome even feasible?
Even setting aside the geopolitical and environmental risks, Golden Dome faces a more basic problem: it may not work.
Yes, it might be able to intercept slower threats like drones or short-range missiles. But against ICBMs, the challenge is exponentially harder.
"Disabling an ICBM in its boost phase is incredibly difficult," Mulvihill says. "That thing is going to be launching within a foreign country – it might be central China or Central Russia – and you’re going to have about two minutes to detect and target it.”
To provide global coverage in that short window, you’d need a staggering number of space-based interceptors.
How many? According to a February 2025 report by the American Physical Society (APS) Panel on Public Affairs, intercepting even a single North Korean ICBM in the boost phase would require more than 1,000 orbiting weapons. Ten missiles launched in quick succession would demand around 10,000.
The cost would be astronomical. The vulnerability to anti-satellite attacks (which countries like Russia are reportedly developing), severe.
The APS report is blunt: “Creating a reliable and effective defence against even the small number of relatively unsophisticated nuclear-armed ICBMs that we considered remains a daunting challenge.
“Our survey of the literature and our analysis of published work has led us to conclude that few of the main challenges involved in developing and deploying a reliable and effective ballistic missile defense have been solved, and that many of the hard problems we have identified are likely to remain unsolved during, and probably beyond, the 15-year time horizon we considered.”
Not another Iron Dome
Golden Dome borrows its name and inspiration from Israel’s Iron Dome – but the comparison is misleading.
"Everybody draws on Israel’s Iron Dome and its success, but you have to remember they defend against much lower altitude missiles and even some hand-held rockets," Mulvihill says. “When you get to ICBMs, it’s a different playing field.”
For now, however, Golden Dome appears to be a go. But Mulvihill is sceptical that it’s about serious defence planning.
“I suspect it’s a lot of political theatre – and an equal amount of opportunism from the aerospace sector,” he says.
About our expert
Michael Mulvihill is a vice chancellor research fellow at Teesside University investigating embodied socio-technical and astro/geopolitical phenomena emerging from nuclear deterrent and space technologies. Additionally, he is an associate convenor of the Military War and Security Research Group and a member of the British International Studies Association Astropolitics Working Group.
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