President Donald Trump has called for an expansive, next-generation missile defense shield for the mainland United States, something modeled on Israel’s formidable defenses, typified by its signature Iron Dome system.

The United States is estimated to have spent more than $400 billion on the kinds of antimissile goals that the president now says will provide “for the common defense.”

The first Trump administration floated a space weapon concept in March 2018: a neutral particle beam in space. But it ultimately shelved the idea because of the massive amount of power needed to destroy a missile with directed energy.