• Lower launch costs could reduce previous estimates for space-based interceptor (SBI) constellation costs by 30-40%.
• Increased ICBM capabilities from North Korea and a presidential executive order to defend against peer adversaries could increase SBI system costs.
• The CBO estimates the lowest-cost SBI alternative would fall from $264 billion to $161 billion due to lower launch costs, while the highest-cost alternative would fall from $831 billion to $542 billion.

The Congressional Budget Office (CBO) released a report on May 5, 2025, analyzing how declines in launch costs affect the estimated costs of deploying a space-based interceptor (SBI) system designed to defend the United States against intercontinental ballistic missiles (ICBMs). While lower launch costs could reduce expenses, the report cautions that evolving threats, such as increased ICBM capabilities from North Korea, and policy changes, including a presidential executive order to protect against peer adversaries, could lead to higher overall costs for an SBI constellation, named "Golden Dome".

• What: The CBO report analyzes the cost implications of deploying space-based interceptors (SBIs) for missile defense, considering reduced launch costs, evolving threats, and policy changes.
• Who: The Congressional Budget Office (CBO), U.S. Senate lawmakers (Deb Fischer and Angus King), the Pentagon, President Donald Trump, and potential adversaries like North Korea, China, and Russia.
• When: CBO report released on May 5, 2025. Previous CBO and National Research Council (NRC) studies published in 2004 and 2012, respectively. President Trump's executive order signed in January (year unspecified).
• Where: Focus is on defending the United States from ICBM attacks, with SBI systems deployed in space.

The CBO's analysis provides a valuable assessment of the financial implications of deploying space-based missile defense systems in a changing geopolitical landscape. While reduced launch costs offer significant potential savings, the increasing sophistication and number of ICBM threats, coupled with a broadened scope of defense to include peer adversaries, necessitates a more expansive and, therefore, more expensive SBI system. The report underscores the complexity of balancing technological advancements with evolving security challenges in national defense planning.

The CBO report suggests that while lower launch costs offer significant potential savings for space-based missile defense systems, the actual costs will likely be much higher than previous estimates due to increasing threats and expanded defense requirements. Further analysis is needed to quantify the impact of these factors. The Pentagon is expected to request funding for the 'Golden Dome' effort in its fiscal 2026 budget, as the United States seeks to develop a layered network of missile defense systems.