A diplomatic cable, also known as a diplomatic telegram or embassy cable, is the term given to a confidential text message exchanged between a diplomatic mission, like an embassy or a consulate, and the foreign ministry of its parent country.
The term cable derives from the time when the medium for such communications was international submarine communications cables. The term cablegram is also sometimes used. Due to the importance and sensitive nature of the subject matter, diplomatic cables are protected by the most elaborate security precautions to prevent unfettered access by the public, and unauthorised interception by foreign governments. They are always encrypted, frequently by unbreakable one time pad ciphers using key material distributed using diplomatic couriers.
^Definition of "cable", The Macquarie Dictionary (3rd ed.). Australia: Macquarie Library. 1997. ISBN0-949757-89-6. (n.) 4. a telegram sent abroad, especially by submarine cable. (v.) 9. to send a message by submarine cable.