The joint US-Canadian military monitoring agency has continued its decades-long tradition of tracking Santa's whereabouts, helping children around the globe find out when his reindeer-powered, present-filled sleigh is coming to town.

A 3-D, interactive website at www.noradsanta.org showed Santa and his reindeer on their imagined worldwide delivery route, allowing users to click and learn more about the various cities along the way.

The Santa tracker presented by the North American Aerospace Defense Command (NORAD) dates to 1955, when a Colorado newspaper advertisement printed a phone number to connect children with Santa but mistakenly directed them to the hotline for the military nerve center.

To avoid disappointing the little ones, NORAD's director of operations at the time, Colonel Harry Shoup, ordered his staff to check the radar to see where Santa might be and update the children on his location.

The tracker on Sunday went down for a short while, leaving children in the Pacific region in the dark about his exact position.

"Hey #SantaTrackers! We may be having a couple of technical difficulties with our tracking map, but #Santa is still flying! He is headed to Fiji next!" said the group which runs the tracker on their Facebook page, before announcing a fix about an hour later.

NORAD also continued the tradition of setting up a temporary call center out of its Colorado headquarters to answer children's burning questions.

A photo posted by the group on Facebook showed rows of people answering phones, some in uniform and others wearing red Santa caps.

When not spreading holiday cheer, NORAD conducts aerospace and maritime control and warning operations — including monitoring for missile launches from North Korea, something that may be on Santa's mind this year as he passes over, with the most recent ICBM test just days ago.