US space-based missile defense could cost $542 billion, CBO says

Tony Capaccio, Bloomberg News on May 5, 2025

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WASHINGTON — The United States may need to spend up to $542 billion over 20 years to develop and launch a network of space-based interceptors, the Congressional Budget Office said, putting a rough cost estimate on an unproven part of President Donald Trump’s proposed “Golden Dome” defense system.

The network for space-based interceptors could cost $161 billion at the low end, the office said in an assessment prepared for a subcommittee of the Senate Armed Services Committee. The price tag will depend on launch costs and the number of weapons put into orbit, it said.

The report updates earlier studies by the CBO and the National Research Council on the cost of space-based missile defenses. Those reviews considered potential intercontinental ballistic missile attacks from U.S. adversaries including North Korea.

The estimates are so rough in part because space-based interceptors are an unproven technology. Trump’s plan hearkens back to President Ronald Reagan’s unfulfilled quest for a space-based missile defense system that was widely known as “Star Wars.”

“Although launch costs are lower now, threats and U.S. policies have changed since those studies were published in ways that could increase the overall size and cost of an SBI constellation,” says the seven-page report, the first authoritative independent government review of President Donald Trump’s vision.

The White House and Pentagon have yet to disclose any details of the initial Golden Dome architecture.

In its assessment, the CBO cited two major factors that could lead to higher costs for space-based missile defense systems: the increasing number and sophistication of North Korea’s ICBMs, and growing threats from Russia and China.

“Such a defense could require a more expansive SBI capability than the systems examined in the previous studies” and “quantifying those recent changes will require further analysis, which CBO is undertaking,” it says.

The report says Golden Dome space-based interceptors intended to counter Chinese and Russian ICBMs “would need to be much bigger — and therefore more costly — than the constellations in the previous studies,” citing potential counter-measures from the two countries, including targeting interceptors with anti-satellite weapons.

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