Children of the world, tune in: Santa Claus is coming, and the North American Aerospace Defense Command is making sure nothing sidelines Saint Nick’s global travels. NORAD, the U.S. military agency responsible for monitoring and defending the skies above North America, has once again launched its Santa tracker as Mr. Claus sets off with his reindeer from his hometown on the Arctic Circle and makes his first stop in Finland. The Colorado Springs, Colorado-based agency’s Santa tracking service allows people to follow his Christmas journey through its noradsanta.org website, social media channels and mobile app. Each year, 150 to 160 volunteers crowd into a conference room at Peterson Air Force Base in Colorado Springs, taking two-hour shifts to answer the phones as eager children call to see if Santa and his sleigh have reached their rooftops. While some callers are able to get through to a member of the military or other volunteer — maybe even the president, on some occasions — when they dial the NORAD Tracks Santa toll-free number, 1-877-Hi-NORAD (1-877-446-6723), others will get a recorded update on Santa’s current location.