How do commanders determine their units' METLs?

Commanders determine their units' METLs (Mission Essential Task Lists) based on war and external directives because these directives provide a framework for the operational environment and the strategic goals that the unit needs to achieve. This approach ensures that the tasks prioritized for training are aligned with the requirements of the broader military objectives and the expected scenarios in which the units might be deployed.

Incorporating war and external directives into the determination of METLs enables commanders to identify the most relevant tasks that need to be mastered to ensure readiness for combat and operational effectiveness. This method allows for a focused training strategy that prepares units to meet mission demands effectively, considering the larger context of national defense and military strategy.

While internal assessments and available resources can inform aspects of training and readiness, they do not provide the overarching strategic guidance that war and external directives impose. Historical performance can offer insights into past effectiveness but does not necessarily shape the present or future objectives according to current military needs. Therefore, relying on external directives is vital for ensuring that units are prepared for current and future conflicts.