secret defense service

Secret Intelligence Service (SIS) / Military Intelligence, Section 6 (MI6)

secret service

Australian Secret Intelligence Service (ASIS)

secret (security classification)

secret

secret agent intelligence

secret internet protocol router network (SIPRNET)

top secret (security classification)

top secret

state secret

be drawn from secret intelligence

be marked top secret

foreign secret agent

give away the secret by careless talk

clear secret

clearance for top secret work

secret clearance

secret language

secret post

secret qualification clearance

secret security clearance

secret text

secret weapon

microdot secret writing

perimeter defense (all-around defense)

beach defense mine / beach-defense mine

Defense Security Service (DSS)

US Army Trial Defense Service

Defense Audit Service

Defense Clandestine Service (DCS)

branch (military/service branch, armed service)

separate from active service / the service