US President Donald Trump’s proposed “Golden Dome” missile defence system could cost as much as $1.2 trillion over the next two decades, according to a new estimate released by the nonpartisan Congressional Budget Office (CBO). The report highlights the potentially enormous long-term financial commitment required for the ambitious defence initiative aimed at strengthening protection against advanced missile threats.

In its assessment released on Tuesday, the CBO said more than $1 trillion of the projected total would be spent on acquisition costs, including the development of interceptor systems and a space-based missile warning and tracking network. The report identified the planned space-based interceptor layer as the most expensive element of the programme, accounting for roughly 70 per cent of acquisition expenses and 60 per cent of overall costs.

The agency also estimated that annual operational and maintenance expenses for the system would average approximately $8.3 billion over the 20-year period. Analysts said the scale of the programme reflects the complexity of developing an integrated missile defence shield capable of countering large-scale aerial and ballistic missile attacks.

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Trump first directed the United States Department of Defense to begin planning the system in January 2025, initially referring to it as the “Iron Dome for America.” The project was later renamed “Golden Dome” and presented as a next-generation national defence architecture designed to protect the United States against increasingly sophisticated missile threats from rival nations.

In May 2025, Trump announced that $25 billion had already been allocated for the initiative and estimated the total cost at around $175 billion. However, subsequent reviews by the CBO suggested the actual price could be substantially higher, particularly due to the technological challenges associated with deploying interceptors in space.

The latest estimate comes as the Pentagon expands the strategic scope of the programme under the 2026 National Defense Strategy. The document states that the military will focus on developing capabilities to “cost-effectively defeat large missile barrages and other advanced aerial attacks,” signalling that the Golden Dome project may evolve into one of the most extensive and expensive defence systems ever undertaken by the United States.

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