The overall goal or objective ET is attempting to accomplish involves many parts all intricately woven together to effect change in their system that would not be possible were they to forgo their actions involving EA.
They are creating a Humine or Humanoid Mine where they harvest Humanoid beings as a slave resource for their system. A Humanoid slave is the most valuable resource in the system to acheive yet it also is the most risky to undertake. Success can position your system above others that have not undertaken the process, failure can result in the end of your system.
The goal is to win a war against the EA so that ET can validate the intellectual and physical enslavement of the EA to other ET systems. The S&T (Strategies & Tactics) are the methods employed to accomplish that goal. The T&C (Terminology & Concepts) are the manner in which the S&T are executed.