This behavior is a specific approach to strategic deterrence that seeks to incorporate nonmilitary and military (nuclear and nonnuclear) means into a continuous spectrum of actions for deterrence, escalation management, and warfighting. Nuclear weapons are the foundation of credible strategic deterrence and signaling with these and other strategic capabilities could in theory be instrumental for deterring the escalation of a local conflict to a regional war.
Russian signaling varies from aggressive declarations from Putin himself but also Russian officials such as Medvedev or journalistic cronies, to medium to large scale strategic exercises like the infamous Grom. Likewise, on the international stage, Russia has shown restraint by reimplementing the Reagan-Gorbachev declaration, but also deliberate disrespect of arms control agreements, notably by suspending its participation to the New START treaty.
In practice, however, Russia’s use of strategic deterrence signaling in this conflict has been met with mixed results insofar as it has not compelled the cessation of or constraints on Western lethal aid to Ukraine, even though it may have, at least in the eyes of Russian officials, deterred direct Western intervention.
Consequently, there might be more to expect from Russia, depending on the evolution of the daily battlefield in Ukraine. If the use of a nuclear weapon is still very unlikely, some other strategic moves in the hybrid domain (cyberattacks, attacks on undersea cables, information manipulation) could also serve as signaling.