Falklands: GCHQ intercept of Argentine signal ("Argentine submarine force commander gives instructions relating to possible submarine threat, and also to reconnaissance mission") ["reconnaissance of the beach and/or disembarkation [word garbled]"] [declassified May 2023]

This decrypted signal (dating to 28 March and apparently signalled to London on 29 March) was one of the earliest indications that an Argentine invasion was imminent. It seems to have been sent to the Argentine submarine Santa Fé. It was among those shown to MT at 1830 on Wednesday 31 March at her room in the House of Commons, the first solid indication that invasion was imminent.

Read other JIC and GCHQ documents from the Falkland War, including the alarmed response of the British Naval Attaché in Buenos Aires.

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