The team -- made up of a bodyguard and driver -- worked for Tom for years, before Tom even met Katie ... and when he and Katie hooked up, Tom assigned the duo to Katie full-time.

The security team worked directly for Katie for years -- but this week Katie appeared with a new security detail made up of 5-6 bodyguards. Neither the old bodyguard nor the driver was anywhere in sight.

Sources connected to the actress tell us, Katie let the old team go after filing for divorce last week -- because of their allegiance to Tom. It's unclear if the duo were Scientologists.