In August 1953, Sâr and Rath Samoeun travelled to Krabao, the headquarters of the Việt Minh Eastern Zone. Over the following nine months, around 12 other Cercle members joined them there. They found that the Khmer Việt Minh was run and numerically dominated by Vietnamese guerrillas, with Khmer recruits largely given menial tasks; Sâr was tasked with growing cassava and working in the canteen. At Krabao, he gained a rudimentary grasp of Vietnamese, and rose to become secretary and aide to Tou Samouth, the Secretary of the Khmer Việt Minh's Eastern Zone.