On 21 January 1968, an aircraft accident, sometimes known as the Thule affair or Thule accident (; Danish: Thuleulykken), involving a United States Air Force (USAF) B-52 bomber occurred near Thule Air Base in the Danish territory of Greenland. The aircraft was carrying four B28FI thermonuclear bombs on a Cold War "Chrome Dome" alert mission over Baffin Bay when a cabin fire forced the crew to abandon the aircraft before they could carry out an emergency landing at Thule Air Base. Six crew members ejected safely, but one who did not have an ejection seat was killed while trying to bail out. The bomber crashed onto sea ice in North Star Bay, Greenland, causing the conventional explosives aboard to detonate and the nuclear payload to rupture and disperse, resulting in radioactive contamination of the area.

The United States and Denmark launched an intensive clean-up and recovery operation, but the secondary stage of one of the nuclear weapons could not be accounted for after the operation was completed. USAF Strategic Air Command "Chrome Dome" operations were discontinued immediately after the accident, which highlighted the safety and political risks of the missions. Safety procedures were reviewed, and more stable explosives were developed for use in nuclear weapons.

In 1995, a political scandal arose in Denmark after a report revealed the government had given tacit permission for nuclear weapons to be located in Greenland, in contravention of Denmark's 1957 nuclear-free zone policy. Workers involved in the clean-up program campaigned for compensation for radiation-related illnesses they experienced in the years after the accident.

The Boeing B-52 Stratofortress is an American long-range, subsonic, jet-powered strategic bomber. The B-52 was designed and built by Boeing, which has continued to provide support and upgrades. It has been operated by the United States Air Force (USAF) since the 1950s. The bomber is capable of carrying up to 70,000 pounds (32,000 kg) of weapons, and has a typical combat range of around 8,800 miles (14,080 km) without aerial refueling.Beginning with the successful contract bid in June 1946, the B-52 design evolved from a straight wing aircraft powered by six turboprop engines to the final prototype YB-52 with eight turbojet engines and swept wings. The B-52 took its maiden flight in April 1952. Built to carry nuclear weapons for Cold War-era deterrence missions, the B-52 Stratofortress replaced the Convair B-36 Peacemaker. A veteran of several wars, the B-52 has dropped only conventional munitions in combat. The B-52's official name Stratofortress is rarely used; informally, the aircraft has become commonly referred to as the BUFF (Big Ugly Fat Fucker/Fella).The B-52 has been in service with the USAF since 1955. As of June 2019, there are 76 aircraft in inventory; 58 operated by active forces (2nd Bomb Wing and 5th Bomb Wing), 18 by reserve forces (307th Bomb Wing), and about 12 in long-term storage at the Davis-Monthan AFB Boneyard. The bombers flew under the Strategic Air Command (SAC) until it was disestablished in 1992 and its aircraft absorbed into the Air Combat Command (ACC); in 2010, all B-52 Stratofortresses were transferred from the ACC to the new Air Force Global Strike Command (AFGSC). Superior performance at high subsonic speeds and relatively low operating costs have kept them in service despite the advent of later, more advanced strategic bombers, including the Mach 2+ B-58 Hustler, the canceled Mach 3 B-70 Valkyrie, the variable-geometry B-1 Lancer, and the stealth B-2 Spirit. The B-52 completed 60 years of continuous service with its original operator in 2015. After being upgraded between 2013 and 2015, the last airplanes are expected to serve into the 2050s.