President Donald Trump's proposed missile defense system dubbed the "Golden Dome" is estimated to cost $1.2 trillion over two decades, according to a new analysis by the Congressional Budget Office. 

The nonpartisan office described the analysis as one that provides "one illustrative approach rather than an estimate of a specific administration proposal," according to the Associated Press. 

Trump had ordered the system in an executive order during his first week of his second presidency, In a series of posts on X, the Department of War described it as a "layered, integrated shield" that will defend the U.S. against ballistic missiles, hypersonic missiles, advanced cruise missiles and next-generation aerial attacks.

"From a NORAD and NORTHCOM perspective, the requirement is clear. To defend North America and win tomorrow's fight, we must maintain our war-fighting advantages and operate beyond stove-piped systems operating at human speed. Golden Dome is forging the integrated, automated battle management network needed to see every threat, make decisions in milliseconds, and keep America safe," said Maj. Gen. Mark Piper, deputy director of operations at NORAD.

The CBO report notes that its estimate lacks many details from the Department of War about what and how many systems would be deployed. This makes it impossible to estimate the long-term cost of the Golden Dome system, the report explains.