The North American Aerospace Defense Command is celebrating its 55th anniversary.
A ceremony is planned Thursday at NORAD's headquarters at Peterson Air Force Base in Colorado Springs, Colo.
NORAD is a joint U.S.-Canada command responsible for defending the skies over both nations and monitoring sea approaches.
It "tracks" Santa Claus every Christmas Eve and also is known for a command post dug deep inside Cheyenne Mountain during the Cold War to protect it from missile attack.
The command post has been moved above ground at Peterson Air Force Base, but the mountain stronghold is maintained as a backup site.
NORAD's commander, U.S. Army Gen. Charles Jacoby, and James Bezan, chairman of the Canadian Parliament's Standing Committee on National Defense, will speak at the anniversary observance.