In 1954 he became a member of the Communist Party of Indochina, 1955 Lao People's Party, whose central committee he was from 1957. He was considered a close confidant of the first Secretary-General Kaysone Phomvihane. In 1962 he became his successor as chief of staff of the armed units of the Pathet Lao. In 1966 he became commander-in-chief of the resulting "Lao People's Liberation Army", which fought with North Vietnamese support in the Laotian civil war against the royal troops. In 1972 he rose to the Politburo of the LPRP.