A model for assessing the mobility of the Fuel Supply System (FSS) of an Operational-Tactical Grouping of troops (OTG) is proposed to support command decisions in dynamic combat conditions. Rapid restructuring of logistics systems and uncertainty in initial data make it difficult to assess whether fuel‑supply tasks will be completed on time. Available approaches rely on static parameters and rarely capture transformation of the system during an operation. The research niche of this article is the development of a probabilistic-analytical tool for quantitative assessment of FSS mobility that explicitly incorporates structural transformation into command-and-control decision support. The purpose of the study is to provide Fuel Service command authorities with a method to estimate the probability of timely task execution and to compare managerial options under uncertainty at a specified confidence level. The research hypothesis assumes that combining probability theory with network-planning methods and transformation parameters yields a more adequate mobility assessment than conventional models. The methodology applies probabilistic modelling and network scheduling to compute expected task durations and execution probabilities. The results include an algorithm for calculating an FSS mobility indicator and a procedure for synthesising and evaluating alternative restructuring options under time constraints. The conclusions confirm that the proposed model improves the reliability of mobility assessment and reduces the risk of fuel supply disruption, thereby increasing the effectiveness of logistical support for troops in OTG operations.