Operación Soberanía (Operation Sovereignty) was a planned Argentine military invasion of Chile started on 22 December 1978 due to the Beagle conflict dispute. The invasion was halted after a few hours and Argentine forces retreated from the conflict zone without a fight. Whether the Argentine infantry actually crossed the border into Chile has not been established. Argentine sources insist that they crossed the border.
In 1971 Chile and Argentina agreed to binding arbitration by an international tribunal, under the auspices of the British Government, to settle a boundary dispute. On 22 May 1977 the British Government announced the decision, which awarded the Picton, Nueva and Lennox islands to Chile.
On 25 January 1978 Argentina rejected the decision and attempted to militarily coerce Chile into negotiating a division of the islands that would produce a boundary consistent with Argentine claims.