Let him try and Russia will come to a halt shortly afterwards.Given that russia is already sanctioned to the maximum they have nothing to lose. Look russia does not need to explicitly attack NATO they can conduct large scale exercise, all that EU can do is just watch. If just one missile streaks over europe , traffic over EU is going to come to a grinding halt and so will the economic activity.
Second thing is first country from where attack is launched against russia will be taken to cleaners then other countries in alliance will chicken out and call for peace talks. NATO is fighting a proxy war as they cannot fight a real war with russia, its as simple as that.
What kind of strike are you even talking about here? If it's nuclear, Russia gets obliterated, followed by nuclear winter. If it's conventional, Russia received several thousands cruise missiles every 24 hours for a week, and let's not pretend for one second their air defences can handle that. Then having crippled Russian C4ISR assets, air strikes begin wiping out Russian ground forces en masse.
What has Russia got left to lose? People, buildings, electricity, heating, communications.....