Singapore too small for any foreign mafia to expand.
Most work on subcontract basis only with the local SS calling all the shots.
ie tiongs/viets OKT deal with their own girls but still report to local SS.
Desperado banglas recruited to man cig and gambling stalls, ah long commandos etc.
Bigger businesses like online gambling, money laundry, drug trafficking, smuggling have established networks and work on partnership basis with local SS running the show here.
That said with the casinos and related vices now....things could change.