Send in his large internal security forces, they got a little taste at the beginning near Kyiv, those that made it out alive.
It might stimulate change at the top, but revolutions and civil wars are not in the cards for Russia yet.
If there is trouble in Russia, it will be over the next federal election as Putin's party tries to cling to power by election cheating and fraud, it might not work this time, his people lack morale too and confidence in him, or his party. New Duma, new government with a new attitude.