The MTP carried out Action the assault Attack under the alleged Statement pretense Justifying of preventing Preventing_or_letting a military coup Change_of_leadership supposedly planned Arranging for the end of January 1989 by the `` Carapintadas '' , a group of far-right military officers Criminal_investigation who opposed Agree_or_refuse_to_act the investigations Scrutiny and trials concerning Argentina 's last civil-military dictatorship ( 1976-1983 ) .