Has anyone seen N°78252?

The United States abandoned a nuclear weapon beneath the ice in northern Greenland following a crash in 1968, a BBC investigation has found.
Its unique vantage point - perched at the top of the world - has meant that Thule Air Base has been of immense strategic importance to the US since it was built in the early 1950s, allowing a radar to scan the skies for missiles coming over the North Pole.

The Pentagon believed the Soviet Union would take out the base as a prelude to a nuclear strike against the US and so in 1960 began flying "Chrome Dome" missions. Nuclear-armed B52 bombers continuously circled over Thule - and could head straight to Moscow if they witnessed its destruction.
Greenland is a self-governing province of Denmark but the carrying of nuclear weapons over Danish territory was kept secret.

Declassified documents that the BBC obtained under the United States Freedom of Information Act indicate that only three of the bombs were accounted for, and that the United States searched secretly for the fourth bomb, without success.

Quote:

By April [1968], a decision had been taken to send a Star III submarine to the base to look for the lost bomb, which had the serial number 78252. (A similar submarine search off the coast of Spain two years earlier had led to another weapon being recovered.)

But the real purpose of this search was deliberately hidden from Danish officials.

One document from July reads: “Fact that this operation includes search for object or missing weapon part is to be treated as confidential NOFORN”, the last word meaning not to be disclosed to any foreign country.

“For discussion with Danes, this operation should be referred to as a survey repeat survey of bottom under impact point,” it continued.

The view was that no-one else would be able covertly to acquire the sensitive pieces and that the radioactive material would dissolve in such a large body of water, making it harmless.

Other officials who have seen classified files on the accident confirmed the abandonment of a weapon.

The Pentagon declined to comment on the investigation, referring back to previous official studies of the incident.

But the crash, clear-up and mystery of the lost bomb have continued to haunt those involved at the time - and those who live in the region now - with continued concerns over the environmental and health impact of the events of that day in 1968.