Because the Russians still aren't sure the Americans (British, French) wouldn't strike back at them. Putin's motto might be, as he says, "the weak get beaten", but after showing a whole lot of weakness over all these years NATO and friends also finally do start to show some strength.

Look at what Trump did when they tested him with their mercenary army by advancing on an American base. What did he do? He smoked them. How did they react? They backed away. The strong don't get beaten.