Non-intervention is all well and good but it is also the policy the West followed towards the Nazi’s in the 30’s.

WW2 could have been stopped before it started if Britain or France marched into Germany (ad they could have won at many points) at any time between 1933 and 1939.

So by arming Zelensky et al, maybe we are creating a monster (unlikely) but maybe we are stopping a much worse monster from starting WW3 (more likely).