 The Thule Air Base (Pituffik), which is not part of any municipality (it is, like the Greenland National Park, unincorporated territory), is a part of the U.S. network of early warning radars, and is an important facility in the recent discussion of the National Missile Defense (NMD).The proposed update of the facility (X-band Radar) to meet the demands of the NMD is controversial within Greenland and Denmark (Greenland is a part of the Kingdom of Denmark).On January 22, 1968, a B-52 crashed 11 km (7 mi) south of the Thule Air Force Base.