In exile, he eventually became a platoon commander in the People's Liberation Army of Namibia (PLAN), the armed wing of SWAPO.
However, he was arrested and detained for SWAPO from 1976 to 1978 in first Zambia then Tanzania for taking part in protests regarding poor living conditions of exiles and organizational corruption.
Following his release in 1978, Moongo moved to Sweden for a short time before returning to Namibia and organizing support for a new political party, SWAPO Democrats.
However, SWAPO Democrats received just 3,000 votes in the 1989 constituent assembly election prior to independence and the party became defunct soon after.
Moongo joined the leading opposition party following independence, the Democratic Turnhalle Alliance, in 1990 and soon became regional chairperson for much of northern and central Namibia.