4-25. During execution, assessment helps commanders visualize probable outcomes and determine whether they need to change the plan to accomplish the mission, take advantage of opportunities, or react to unexpected threats. Assessment includes both monitoring the situation and evaluating progress. Monitoring—the continuous observation of those conditions relevant to the current operation—allows commanders and staffs to improve their understanding of the situation. Evaluation—using indicators to measure change in the situation and judge progress—allows commanders to identify variances, their significance, and if a decision is required to alter the plan. (See chapter 5 for a detailed discussion on assessment.)