Enforcer

"'Heavy defense drone equipped with rocket launchers. Repels auto-cannon fire. Equipped with energy shield.'""― in-game description of the Enforcer."Enforcer is an enemy unit in Modern Command. It is equipped with energy shield and is immune to auto-cannon rounds (Unless you use AC-AOF "Tremor" rounds). It attacks the base with missiles.

Strategy
You will want to dispose of it quickly, since, as with any missile-launching enemies, it can deal considerable damage even with defensive barrier still on. Its near immunity to auto-cannon fire means that an anti armor missile might be needed. Another option is to use a railgun. Blink and Flash will be hindered by the energy shield but Torrent is able to take care of it on its own. These units are slow and resilient, but several missiles will take it down, even with the shields.