# Value Stream Analysis in Military Logistics:
## 2 Background  
### Military Logistics and Processes  
The supply chain management concept is a horizontal strategic function that encompasses all the operations of the supply chain between customers and suppliers, distribution, manufacturing, procurement, and planning, to give an integrated answer to the competitive difference of the organizations. Viewed from the life cycle perspective, military logistics is the bridge between the deployed forces and the industrial base that produces the weapons and materials that the forces need to accomplish their mission [22]. The North Atlantic Treaty Organization or NATO defines logistics in [23] as the science of planning, coordinating, and carrying out the movement and maintenance of forces, which covers aspects of military operations related to material, transport of personnel, acquisition of facilities and services, and medical service support. Three main aspects of logistics need to be highlighted in the military logistics cycle: production or acquisition logistics focused on the procurement of the material; in-service logistics that links production and consumer logistics and comprises functions associated with receiving, storing, distributing, and disposing material to the force; consumer or operational logistics that concerns the reception, storage, transport, maintenance, and disposal of the material, including the provision of support and services. Depending on the strategic, operational, or tactical level of the logistic function approached, different activities are encompassed. There are also multiple logistic functions identified in the military field. Nevertheless, we will focus on the material supply logistic function in this work, which includes the determination of stock levels, provisioning, distribution, and replenishment restricted in this case to operational and tactical levels. The organization of this research study is referred to as ABC throughout this paper due to non-disclosure requirements. Particularly, ABC is a military unit of the Spanish Army in charge of the supply and maintenance of a wide range of items used as spare parts. Therefore, these supply and maintenance processes could be classified into operational and tactical levels. There are several particularities that make the military supply especially critical [2]. In brief, the large number of different material references, variable demand and multiple ordering locations, priority requirements and high material availability are reasons to justify the necessity of optimizing the material order processing procedure and its metrics in ABC. The process to be optimized starts with an order generation from a deployed military unit that requests the material to ABC, and it ends before the transportation to the final destination [24]. Additionally, for the ABC product families, a critical aspect need to be highlighted, i.e., the high rate of technological obsolescence of the material. The importance of spare parts management in organizations has been addressed in the literature. Supply chain management for spare parts is described in [25] as a multi-echelon supply chain, where the differences in size generate demand peaks and, thus, a very variable and lumpy demand pattern. The authors propose an algorithmic solution considering the sources of demand variability, a probabilistic forecast, and inventory management. The importance of spare parts logistics is mostly related to their inventory management, whose main differences to general inventory management are the low demand and a wide variety of items with no predictable demand. The authors in [26] discuss the basic principles affecting the management of spare parts logistics, which affect the strategic choices and related policies in this area. The most relevant control characteristics of spare parts (criticality, specificity, demand pattern, and value) are first identified to define further supply chain management strategies.