Inside the KSA and its successor organizations, there was a secret organization known as the Cercle Marxiste (Marxist circle). The organization was composed of cells of three to six members with most members knowing nothing about the overall structure of the organization. In 1952, Pol Pot, Hou Yuon, Ieng Sary and other leftists gained notoriety by sending an open letter to Sihanouk calling him the "strangler of infant democracy". A year later, the French authorities closed down the KSA, but Hou Yuon and Khieu Samphan helped to establish in 1956 a new group, the Khmer Students Union. Inside, the group was still run by the Cercle Marxiste.