Further, the anti-war left is not monolithic. A segment of the anti-war left is pacifist. They believe that war is inherently wrong and futile. They believe that non-violent resistance is far superior to taking up arms and point to Gandhi, Mandela and the US civil rights leaders as evidence that non-violent resistance is effective and superior to war. The true pacifists universally condemn violence, both as acts of aggression and in self defense. They do not go around saying "Russia is bad for invading, but they do have some good args and the US is more at fault than Russia . . . ."
Then, there is an anti-war left that is not pacifist. Noam Chomsky is probably the best example. Their priority is avoiding war by diplomacy, arms treaties, etc. But they are not against using force for self defense. Chomsky's view on the Ukraine conflict is that Russia committed a crime of aggression and Ukraine has a fundamental right of self defense. But Chomsky also takes the US to task for its diplomatic failures that lead to the invasion. Chomsky basically claims that if you poke a pit bull and it bites, you shouldn't have poked it. But the pit bull doesn't get to run loose around the play ground.
Finally, there is an anti-war left that horse shoes with the right in taking the position that Ukraine should not be allowed to defend itself with any aid from the West because the West is inherently imperialist and any military aid to Ukraine makes Ukraine imperialist by some sort of political transitive property. Thus, the war is just a proxy war. This segment of the anti-war left breaks from the prior anti-war left in its efforts to somehow justify Russia rolling over Ukraine, which is what would certainly happen if the West did not provide military and financial support to Ukraine. This is where it is hard to discern Russian propaganda from true anti-war leftists. The Gray Zone-ers (Mate, Blumenthal) and the RT/Ruptly vets (Ritter, MacGregor, Lee Camp) and others like Greenwald and Jimmy Dore.