Missing: One US Nuke

When a nuclear-armed B52 bomber scanning for incoming Soviet missiles crashed into the ice on January 21, 1968, scattering its four bombs which detonated but failed to set off their unarmed warheads, a great search was launched. But when fragments were found from only three of the weapons the US launched a submarine search for the missing bomb, being careful to disguise the nature of their secret mission from Danish officials. Forty years on, the missing nuke remains unfound on the sea bed.