Dorothy

“Over the past 40 years, rather than lessening, the threat from next-generation strategic weapons has become more intense and complex with the development by peer and near-peer adversaries of next-generation delivery systems,” Trump said in his executive order, justifying the need for the missile defense system.

And because the US Department of Defense still hasn't delivered key details about the proposed system, the CBO wrote, it is currently "impossible to estimate the long-term cost" of the initiative.

The concept for the missile system is at least partly inspired by Israel’s multitiered defenses, often collectively referred to as the “Iron Dome,” which played a key role in defending it from rocket and missile fire from Iran and allied militant groups as it prosecutes the war on Iran alongside the U.S.

Trump has said that he was inspired to develop such a missile system after being impressed by Israel’s “Iron Dome," despite the fact that Israel has a vastly smaller landmass to defend compared to the US and has historically faced far more danger from missile and rocket attacks.

The U.S. Golden Dome is envisioned to include ground and space-based capabilities able to detect, intercept and stop missiles at all major stages of a potential attack.

Congress has already approved roughly $24 billion for the missile defense initiative through Republicans’ massive tax and spending measure signed into law last summer.

Sen. Jeff Merkley, D-Ore., who requested the estimate from the CBO, said in response to the report that the missile defense project is “nothing more than a massive giveaway to defense contractors paid for entirely by working Americans.”