The US secretly abandoned a nuclear weapon forty years ago after it was lost beneath the ice in northern Greenland, according to a BBC report.

The Beeb's claims are made citing declassified documents obtained under the US Freedom of Information Act and people involved in the unsuccessful search.

The US military's Thule Air Base was considered to have particular strategic importance in the Cold War, equipped with radar to scan for a possible Soviet Union missile attack from over the North Pole.

Because the Pentagon believed the base was a likely target for a Soviet strike, the military had nuclear-armed bombers circle over the site ready for an attack on Moscow.

In January 1968, a B-52 bomber carrying four nuclear devices crashed several kilometers from the base. The explosives surrounding the weapons detonated without setting off the nuclear devices, which hadn't been armed by the crew, the BBC said.

Military personnel and Danish workers spent months afterward searching the ice for tiny pieces of radioactive debris. But despite the Pentagon's claim that all four weapons were "destroyed," in piecing together the fragments only three nukes were actually accounted for.

The documents also allegedly report a suspicious blackened section of ice with re-frozen shroud lines from a weapon parachute.

Scientists fearing the burning parts had melted through the ice sent a Star III submarine to search the ocean floor. In order to maintain that all had gone well with cleanup, the true purpose of the mission was hidden from Greenland officials, the broadcaster claims.

But the underwater search was unsuccessful due to a combination of technical problems and the ice freezing over for the winter. The military eventually abandoned the recovery, believing it unlikely any classified elements could be recovered by another country and that the radioactive material would soon enough dissolve in the ocean.

Now where have we heard this story before...? ®