Think $151 Billion Is Expensive for Golden Dome? Try $1.2 Trillion.

President Trump's Golden Dome missile defense system was announced by executive order in January 2025, and contracts began rolling out last December. For a starting price of $151 billion, the Pentagon would construct an American version of Israel's Iron Dome missile defense system to protect the United States from attack by "ballistic, hypersonic, and cruise missiles, and other advanced aerial attacks." And this price might eventually rise to $175 billion or even $185 billion.

Even just $151 billion would make Golden Dome one of the most expensive defense projects ever undertaken by the Pentagon. And as it turns out, $151 billion was the lowball price.

Now we know Golden Dome will cost $1.2 trillion.

Image source: Getty Images.

"[$1.2 trillion] for defense, not one cent for tribute"?

This new number isn't a rumor, a guess, or even an estimate. It's the official projection from the Congressional Budget Office (CBO) on the cost of building Golden Dome over the next 20 years. It also has serious implications for investors wanting to buy shares of defense companies, both large (Boeing (NYSE: BA), Lockheed Martin (NYSE: LMT), and RTX Corporation (NYSE: RTX), for example) and somewhat smaller (Intuitive Machines (NASDAQ: LUNR), Rocket Lab (NASDAQ: RKLB), and Viasat (NASDAQ: VSAT) among them) that have already won Golden Dome contracts.

Because the more you learn about Golden Dome and its price tag, the less likely it becomes that this thing will ever get built.

Golden Dome by the numbers

Consider just a few of the CBO's findings. CBO breaks down Golden Dome into six major "system components," plus a seventh, $92 billion catch-all covering research and development costs. Starting at the bottom, and moving up, Golden Dome will probably comprise:

• Self-defense for existing ground-based missile defense rocket bases: $4 billion over 20 years.
• An expanded network of ground-based interceptor missiles covering low-flying missiles: $29 billion.
• Even more ground-based interceptor missiles targeting upper-atmosphere threats: $46 billion.
• Orbiting satellites carrying space-based interceptor missiles: $90 billion.
• Ground-based interceptor missiles covering entire regional theaters of defense: $187 billion.
• And finally, 7,800 space-based interceptor (SBI) missiles costing $743 billion.

Add it up, and CBO estimates the 20-year cost of Golden Dome at $1.2 trillion -- $1.191 trillion to be precise. Just buying all the materiel to assemble the system will cost $1 trillion. After that initial investment, operating and maintaining it over time will cost $8.3 billion per year.

And even that number is optimistic.

The trouble with Golden Dome

As defense news site TWZ correctly pointed out earlier this week, it's the last item on the list that's having the greatest impact on Golden Dome's cost. Buying 7,800 SBI missiles will cost $723 billion up front, plus $1 billion per year to maintain.

And here's the real problem: To be placed in close enough proximity to a hostile missile to destroy it within minutes of launch (in its boost phase when it's most vulnerable), the satellites that carry these SBI missiles must orbit close to Earth -- roughly 300 to 500 kilometers. Low-orbiting satellites by definition cannot remain in orbit for long -- perhaps five years before they slow down and burn up in the atmosphere. Thus, 20% of the SBI fleet must be replaced annually.

That's 1,600 more SBI missile satellites that must be replaced per year, every year, forever. Over just the first 20-year time span, this works out to "roughly 30,000 satellites" required -- three times more satellites than even SpaceX has launched since it became a company. (Side note: CBO believes SpaceX's Starship will be essential to providing the launch capacity to build Golden Dome in the first place.)

The other trouble with Golden Dome

So even $1.2 trillion is just the new starting point for Golden Dome's cost. But after spending so much, will Golden Dome at least be "worth it"?

This raises the next big issue with Golden Dome: capability.

Because Golden Dome's SBI interceptors aim to defeat threats at their source, the satellites cannot cluster over the United States alone, forming a "dome." They must instead form a globe, encompassing the whole Earth, covering every country that might pose a threat and every inch of ocean where a nuclear submarine might lurk.

Spread out in this manner, only a few SBIs would be close enough to engage a threat at any one time. CBO estimates that at best, Golden Dome could protect America from no more than 10 missile launches at a time.

Although it's an admirable idea in theory, I fear the Golden Dome will ultimately be deemed too expensive and impractical to justify building. It may take years and billions of dollars before Congress comes to the same conclusion, but my prediction is Golden Dome will end up canceled far short of completion.

Rich Smith has positions in Intuitive Machines and Rocket Lab. The Motley Fool has positions in and recommends Boeing, Intuitive Machines, RTX, and Rocket Lab. The Motley Fool recommends Lockheed Martin. The Motley Fool has a disclosure policy.