Soon after taking office , Rhee enacted laws that severely curtailed political dissent . There was much controversy between Rhee and his leftist opponents . Allegedly , many of the leftist opponents were arrested and in some cases killed . The most controversial issue has been Kim Gu 's assassination . On 26 June 1949 , Kim Gu was assassinated by Ahn Doo-hee , who confessed that he assassinated Kim Gu by the order of Kim Chang-ryong . The assassin was described by the British historian Max Hastings as one of Rhee 's " creatures " . It soon became apparent that Rhee 's governing was going to be authoritarian . He allowed the internal security force ( headed by his right-hand man , Kim Chang-ryong ) to detain and torture suspected communists and North Korean agents . His government also oversaw several massacres , including the suppression of the Jeju uprising on Jeju island , of which South Korea 's Truth Commission reported 14,373 victims , 86 % at the hands of the security forces and 13.9 % at the hands of communist rebels , and the Mungyeong massacre
Mungyeong massacre
Mungyeong Massacre
Syngman Rhee