Cold War: Two <a href="https://en.wikipedia.org/wiki/Cryptography" id="mwyQ" rel="mw:WikiLink" title="Cryptography">cryptographers</a> working for the United States <a href="https://en.wikipedia.org/wiki/National_Security_Agency" id="mwyg" rel="mw:WikiLink" title="National Security Agency">National Security Agency</a> left for vacation to Mexico, and from there <a href="https://en.wikipedia.org/wiki/Martin_and_Mitchell_defection" id="mwyw" rel="mw:WikiLink" title="Martin and Mitchell defection">defected to the Soviet Union</a>.