Free_Press, 
"We know when Putin feels threatened, he makes a preemptive strike to his perceived enemy
I believe Putin feels threatened by his own military and axed Shoigu to cut the head off the snake
Naming a civilian as his Defense Minister means two things...
He felt threatened by the military Shoigu led
Russia's economy is in tatters and for Putin to succeed in the field of battle, the economy and war must be joined for a LONG war