The men who tracked the USSR's nuclear rise kept their findings buried in layered bureaus for decades, hiding the gap between what they knew and what they told the public.
Millions of lives were balanced against technical specifications kept secret for decades, though the records of the UK Ministry of Defence still mask how the data was gathered.
Hidden within the UK Ministry of Defence, the record of a clandestine nuclear program on a densely populated island was kept from public view while the risk of proliferation grew.
A meteorologist who led two universities was tracked for years by the UK's Division of Atomic Energy Intelligence, a record that remained hidden until its release.
Marked confidential for years, the record shows Boris Yeltsin’s failed effort to remove the briefcase of nuclear apocalypse from the hands of military aides.
He volunteered his services to the KGB and GRU, handing over damaging data that accelerated the nuclear arms race while hiding behind a British passport.
Soviet handlers ran a British physicist for seven years while he leaked nuclear secrets, a betrayal recorded in the Security Service's PF series files.
American nuclear forces and technical patents were targeted by African presidents and communists in Brussels seeking to choke Seoul's industrial capacity.
Nikita Khrushchev was accused of surrendering to the West in a hidden 1963 rift where Kim Il Sung rejected the Moscow Treaty and urged other socialist states to seek nuclear weapons.