Step 1 : Introduction to the question "Where is the U.S. Thule Air Base located?"
...Thule Air Base is 750 miles north of the Arctic Circle on the northwest side of Greenland. The base is home to the global network of sensors, a vital part of the 21st Space Wing. This network provides missile warnings and space surveillance. It also provides space control to Air Force Air Command and North American Aerospace Defense Command. Thule Air Base also claims bragging rights as the world's northernmost deep-water port. Source: Peterson.AF.mil
