This is reason enough, but if you agree with Kasparov, which I do; we are already in WW3. putin has already determined this and is treating it as such, it's a matter now of whether or not it is limited to just Ukraine. If the Ukrainians do not win, and are ultimately defeated here (which I do not believe will happen), then it is just a matter of time before Russia does this again in Estonia, Latvia, Lithuania, Moldova, Romania, Georgia and anywhere else they think they can get away with this. The stakes are freedom in Eastern Europe and at least some of central Asia, with or without putin (if unchecked, whomever succeeds putin will likely act in the same manner). A defeated and broken Russia leads to the possibility of at least some internal change in Russia for the positive. Otherwise, we are going to be subject to nuclear blackmail on a global stage and Russia will continue wars of aggression and terror. We've been down this road to before, and our failure to act has lead us to where we are now, it needn't continue.