sentences:  Most of those involved in the rioting were well-known and particularly-infamous members of local Singapore secret societies who were detained without trial and had little to no hope of leaving the island for the rest of their lives.As a result of the terrible riot, the experimental penal settlement was shut down and the programme came to an abrupt end by the end of 1964, with the island being declared out of bounds to all.Since 9 June 1989, the island, together with Pulau Pawai and Pulau Sudong, form the Singapore Armed Forces (SAF) Southern Islands Live-Firing Area (SILFA), a restricted military training area and live-firing zone.