My apologies to all.....My info above is wrong....the description should be for FDS...
..I attach the correct info below....taken from the RSAF website....
Field Defence Squadron (FDS)
The Field Defence Squadron ensures the security of the air base through regular perimeter patrols and controlling personnel movement within the base. During operations, it provides ground defence of the air bases against enemy infiltration. The FDS operates at all four air bases.
HQ ADSD's SSSO acts to advise and direct FDS personnel on matters pertaining to tactical and strategic operations, training, professional upgrading and career advancement.