Thanh , leader of the Khmer Serei , had recruited FANK reinforcements amongst the Khmer Krom of southern Vietnam .
The loyalty he commanded amongst these comparatively elite , US - trained troops meant that his support for the Republic 's fragile government remained essential .
Thanh , leader of the Khmer Serei , had recruited FANK reinforcements amongst the Khmer Krom of southern Vietnam , and the loyalty he commanded amongst these comparatively elite , US - trained troops meant that his support for the Republic 's fragile government remained essential .