As its main goal, the article advocates the rationality of the concept of equilibrium in secure strat- egies (EinSS) and the organic proximity of the logic of this concept to the logic underlying the classical approach to solving game-theory problems through Nash equilibrium. The article examines in detail the sys- tem of EinSS definitions through the prism of the Nash equilibrium concept. Based on this analogy, the con- nection between the existence of EinSS and the existence of a Nash equilibrium is established.