A top Russian official warned an advanced U.S. missile defense shield move could lead to military "confrontation" in space.

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.

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.”