Changed headline, adds context in paragraphs 2 and 3

By Mike Stone

WASHINGTON, May 12 (Reuters) - The nonpartisan Congressional Budget Office estimated on Tuesday that U.S. President Donald Trump's Golden Dome missile defense shield could cost approximately $1.2 trillion to develop, deploy and operate over 20 years, a figure that dwarfs an $185 billion price tag offered by the program's Pentagon director.

Golden Dome envisions expanding ground‑based defenses such as interceptor missiles, sensors and command‑and‑control systems while ​adding space‑based elements meant to detect, track and potentially shootdown incoming threats from ​orbit. These would include advanced satellite networks and orbiting weapons.

The CBO estimated acquisition costs alone for the system would total just over $1 trillion, with the space-based interceptor layer — a constellation of 7,800 satellites — accounting for about 70 percent of acquisition costs.