<s>[INST] Historians widely agree that one of the primary justifications for the Soviet invasion of Afghanistan in 1979 was...vacillation.  The power struggle between Hafizullah Amin, an apparently pro-Soviet communist puppet president, and his predecessor Nur Mohammad Taraki, resulted in the assassination of the latter and the consolidation of the former.  What were four primary arguments used by Soviet authorities to rationalize this crucial abstention from sovereignty?[/INST]