That is quite a sentence.
The key word to understand in this sentence is "measures". The sentence is talking about Measures of Effectiveness.
Measures are tools the military uses to determine if a mission is effective or not. Measures are based on information that tells the planners how well the the operation is succeeding, how much effort it takes to accomplish tasks, whether the effort is worth the cost, etc.
-the more general measures identified during the precrisis period...........these are the measures the military uses to determine ahead of time whether they should become involved in a humanitarian or military crisis. This is information about the political situation, other aid agencies, the involvement of other countries, georaphy, etc.
-tailoring the measures to the specific objectives required at the mission level.......after the military has decided to intervene in a crisis they use other more precise information to measure the success or failure of the objectives of the mission: political, humanitarian, military, etc
-the military and humanitarian tasks to be performed...........the military will measure the effectiveness of the humanitarian and military tasks that the soldiers perform and perhaps decide when it is time to end the mission
- and the application of effort against these tasks..........they will measure the effort it takes to accomplish the tasks, whether it is too difficult for the military personnel, whether it is worth the cost, etc.