1-12. The complex and dynamic nature of an operational environment makes determining the relationship between cause and effect difficult and contributes to the friction and uncertainty inherent in military operations. Commanders must continually assess their operational environments and re-assess their assumptions. Commanders and staffs use the Army design methodology, operational variables, and mission variables to analyze an operational environment to support the operations process. (See paragraphs 4-7 through 4-8 for a discussion of the Army design methodology.)