Along with Tou Samouth, Son founded the Kampuchean People's Revolutionary Party (KPRP) in 1951. After the Geneva Agreements and the end of the First Indochina war, he and many Khmer Issarak officials left Cambodia for North Vietnam.
In 1951, Son, alongside Tou Samouth, established the Kampuchean People's Revolutionary Party (KPRP). Following the Geneva Accords and the conclusion of the First Indochina War, Son and numerous Khmer Issarak officials relocated to North Vietnam.