The chapter explores the factors that have enabled four de facto states in the post-Soviet space to sustain their existence for more than a quarter of a century. Unlike the popular discourse which often considers de facto states as mere puppets of their powerful patrons, the author claims that the security guarantees provided by an external patron are just a part of the complex phenomenon of a de facto states’ sustainability. Whereas the military, economic, or political support from a patron state is crucial for a de facto state to prevent its reintegration into the parent state, the internal viability of a de facto state is crucial to survive as a distinct polity, and to not be absorbed by its powerful patron.