Trump estimated the Golden Dome project to cost $175 billion, with a $25 billion down payment. A recent Congressional Budget Office estimate put the total cost of deploying and operating a constellation of space-based interceptors for 20 years at anywhere from $161 billion to $831 billion.

Experts are divided whether a new missile defense system for the U.S., inspired by Israel's Iron Dome, would be worth the cost. Trump wants a Golden Dome over America. Here's what it would take ...