"We should support whatever the enemy opposes and oppose whatever the enemy supports."
https://www.marxists.org/reference/archive/mao/works/red-book/quotes.htm
For a better context, see this: https://hexbear.net/comment/3563148
It makes more sense to "support" Putin because this conflict is not happening in a vacuum and its outcome also is important to the conflict between Russia and NATO. Wagner winning would probably represent -- at best -- another 1993 and may in fact be much worse depending on the influence of genuine Nazis. Mutual destruction would also, much more directly, represent another 1993 because it would mean NATO can roll in whether via tanks or corporate stooges and take over.
Third campism is trot bullshit and should not be supported.
Also the comment right below that one:
To be fair, most Western leftists never read Mao so they never understand why Trotskyism will never work in the third world (yes I consider Russia to be a third world resource colony to the neoliberal West).
Mao gave a special place to the (Chinese) Trotskyists and equated them to 汉奸 (lit. Han Traitors, or traitor to the Chinese people), which is probably the worst insult you can ever get from someone like Mao.
The Trotskyists wanted the Chinese communists to do Lenin’s “revolutionary defeatism” by abandoning collaboration with the national bourgeoisie (i.e. the KMT), but instead act on defeating the KMT government right when the Imperial Japanese Army was rampaging through China. According to the Trotskyists, solidarity with the working class of other countries is all that is needed, and they were willing to let the Japanese imperialists conquer the mainland if that could lead to some universal solidarity among the oppressed class.
This is how fascism wins. The Chinese Trots were hated throughout the country and it would take until the 1970s to see a small resurgence among the Hong Kong leftists.
This is why those of us who grew up reading Chinese history just roll our eyes when we see Western leftists calling for “revolutionary defeatism” in Russia because the exact same thing happened to China more than 80 years ago! The defeat of the bourgeois government in Russia means the victory of the fascists and Western imperialists.
Once again, read Mao (start with the Selected Works of Mao Zedong).
Same link: "As for unjust wars, World War I is an instance in which both sides fought for imperialist interests; therefore, the Communists of the whole world firmly opposed that war. The way to oppose a war of this kind is to do everything possible to prevent it before it breaks out and, once it breaks out, to oppose war with war, to oppose unjust war with just war, whenever possible."
The quote OP pulled out is – look at it! – an incredibly slippery quote to use out of context and could be used to justify almost anything if applied foolishly.
In the words of a much smarter person: https://hexbear.net/comment/3563148