On January 21, 1968, a United States Air Force B-52 Stratofortress carrying four B28FI thermonuclear bombs caught fire over North Greenland. The crew was forced to bail out, and the pilotless aircraft crashed onto the sea ice in Starvation Bay, four miles from Thule Air Base. The impact detonated the high explosives within the nuclear weapons, shattering the warheads and spreading radioactive material, including plutonium, uranium, and tritium, across a broad swath of ice.
The Pentagon immediately launched Operation Crested Ice, an intense salvage and decontamination operation in sub-zero Arctic conditions. Workers melted hundreds of thousands of gallons of contaminated ice and recovered thousands of fragments from three of the nuclear weapons. However, when intelligence officers painstakingly assembled the debris like a giant jigsaw puzzle, they discovered an alarming discrepancy: key components of the second stage of weapon number four were missing.
Declassified documents and investigative reports later revealed that the heavy secondary fusion stage had likely penetrated the sea ice during the high-speed impact and sunk to the bottom of Baffin Bay. Despite underwater sonar searches, the missing nuclear material was never recovered, leaving a permanent remnant of Cold War nuclear history resting beneath the Arctic seabed.