This chapter describes an application of decision support systems to conflict modelling in information operations recognition. An information operation is considered as a complex weakly structured system. We suggest a model of conflict between two subjects, based on the second-order reflexive model. We describe a method for construction of the design pattern for knowledge bases of decision support systems. We also suggest a methodology allowing to use decision support systems for modelling of conflicts during information operations recognition. The methodology is based on the use of expert assessments and content monitoring data. Keywords: Information operation recognition; Decision support system; Knowledge base; Content-monitoring system; Reflexive model; Conflict modelling.