Residents and tourists remained rattled after the mistaken alert was blasted out to cellphones across the Hawaiian Islands.
The plan, not yet approved by President Trump, is intended to make nuclear conflict less likely.
Local officials quickly recognized Saturday's false alarm, but it took about 40 minutes to notify Hawaii residents.
The Hawaii Emergency Management Agency is trying to determine what caused the false alarm.
A North Korean missile launched last April crashed into a town near Pyongyang, possibly causing an explosion and casualties.
The rocket would be outfitted with re-entry capability -- a feat North Korea's last ICBM wasn't able to achieve.
Lockheed announced it received a five-year $110 million contract from the lab to build the "Gray Wolf."
Lockheed Martin Corp. launched the AGM-158C LRASM from a B-1B Lancer, at Point Mugu Sea Range, California.
NATO fears the system contravenes the 1987 Intermediate-range Nuclear Forces Treaty.