Original sentence: In order to avoid a repetition of the Snipe Incident, Chile placed defensive troops on Snipe and their other islands south of the Beagle Channel before the Operation Soberania, Argentina's planned invasion in 1978
Edited sentence: Thirty years later, in 1978, in order to avoid a repetition of the fait accompli, Chile placed defensive troops on Snipe and their other islands south of the Beagle Channel before the start of Operation Soberania, Argentina's planned invasion