I don't really understand the motivations behind the statement, and it hasn't been reported on particularly widely in the more serious news outlets, so I think it's probably just your normal day-to-day sabre rattling. An attack on NATO seems a particularly unlikely step for Putin to take.
To save the planet from Climate Crisis and other matters, the only way that will work is a unified planet. That will never happen when there's Russia (and co.) who want to dominate the planet.
A great place to start would be taking Kaliningrad and thereby better geographically unifying the Baltic countries with the EU, instead of Russia succeeding by linking itself with Kaliningrad by taking the Suwalki Gap.
We need to start preparing for war. No, we should have already been prepared for war a long a time ago -- we should have already gone to war and won by now. But better start now than even later.