By the early 90's the world of S.D.Z.A. was in utter chaos - with the resulting depletion of the Population, many Police Groups, Army Bases, and Security Forces found themselves with seriously reduced numbers of active personnel - and so, the Sentry programme began.
Sentry Units were first created by Blackwood Industries as an automated defense Drone. Their purpose was a simple one - they could be programmed to protect and individual or location against a Specific Threat by loading their sensors with the Targets genetic code, this focuses their attention on their "targets" (Carrion, Dinosaurs, Truebreeds etc) and made them Harmless, to other life forms.
So far they have been drafted into service by the D-Rangers and the A.S.P. Troopers - though for some reason the F.O.N. Operatives of the Initiative seem to distrust them.
Some time later it came to light that Uni-Tech had their own (secret) Sentry Program - one with a more sinister Purpose, to eradicate Primes, Brotherhood, and Rebels.
Over the years Sentrys have been stolen by various shady organizations, and reprogrammed to fit the needs of their new Masters - leaving them both a useful ally and a threat worldwide.
