Bellingcat investigator says Russia's defense minister Shoigu and other senior officials, possibly including Putin, are residing in nuclear bunkers near Ufa in the Ural mountains, according to recent flight data
I reckon they're hiding there afraid not of nuclear war but possible consequences of well over 20,000 Russian troops killed so far, Russian army surrounded in many parts of Ukraine by the determined Ukrainians and facing a certain rout. As well as the very likelihood of the Ukrainian army marching onto Crimea and taking it back.
The Russian security establishment have destroyed Russia's security and by the end of the year I expect NATO troops will be stationed in East Ukraine and in Crimea.