In 1981, the White House released a secret memo regarding the stockpiling of a certain weapon. What kind of weapon? Now that it's been declassified, we still have no idea: the title remains censored.
The document is called "National Security Decision Directive (NSDD) 7" and was obtained by the Federation of American Scientists. It doesn't leave much room for interpretation: it's simply titled "[REDACTED] WEAPONS". Whatever the weapon is — FAS speculates it's referring to "enhanced radiation" neutron warheads — the memo states the arsenal is only allowed on US soil, and deployment can only be approved by the US President and US Secretary of Defense. Maybe in another three decades we'll know. The full document is embedded below. [FAS]