The joint US-Canadian military monitoring agency has continued its decades-long Christmas 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 3D, interactive website at www.noradsanta.org showed Santa Claus 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 Old Saint Nick might be and update the children on his location.

Sixty-eight years later NORAD is continuing 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.

Some top-level US dignitaries — namely President Joe Biden and wife Jill Biden — joined in on the holiday action.

"This evening, the President and First Lady participated in the North American Aerospace Defense Command Santa tracking calls with children and families across the country," the White House said in a statement.

Earlier Sunday the tracker 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!" the group which runs the tracker said on their Facebook page, before announcing a fix one hour later.

Father Christmas had begun his journey with an out-of-this-world first stop, according to NORAD: the International Space Station orbiting Earth.