"If you liked the president's border wall, wait until you see his space wall," arms control expert Joseph Cirincione said.
An interceptor missile was fired from a U.S. Navy ship.
The U.S. missile defense system was one of the newest additions to its military capabilities.
The U.S. has threatened to impose sanctions on Turkey in a bid to stop it buying the S-400 from Russia.
Moscow alleges that the missile defense systems violate the 1987 Intermediate-Range Nuclear Forces Treaty.
North Korean missiles could use decoys and cooling shrouds to trick U.S. defense systems.
The exercise was carried out in cooperation with the U.S. Missile Defense Agency.