There is another approach which is both similar and different to the above. It's on the lines of U.S. Foreign Policy in Perspective: Clients, enemies and empire the book I started to talk about here >>54223

Based on that we could divide the military options to over and covert. The US can act overtly if the enemy disgraced herself properly in the eye of the international community. If not then uses covert tools >>54316
1. Coups d'état
2. Punctuated military operations
3. Aid to internal armed opposition forces - ie. Guerillas
Basically all means proxy forces in different roles. I do think a coupist group within the army can be considered as proxy force - it acts on behalf of the US.
Already a proxy war is going, but there is no such tool as using proxy and start a war against an enemy. And this is not what happened, since Russia was cornered in to the point Moscow had no option but to start a war themselves. Ukraine became a proxy for military operations after the war started.
What they do is #2 - punctuated military operations: they organize raids with the promise of building a resistance, a guerilla activity, a rebellion, etc. These aren't really successful.

In another context, drawn up in the same book, the US is doing client maintenance via intervention: Ukraine is a client which needs help to maintain the regime because she faces an outside attack. Relevant starts here: >>54271
They get emergency military aid and advisors. So that's one box to tick.
But what to select from here: >>54272 ???
Since the others involve US troop deployment really only one left: Mambo #5 Incompetent clients: basket cases. Not very flattering title. But this is about proxy forces and as situation evolves it might not have started like this maybe it did tho... right now it gets more fitting by the day.
And we arrived to this >>54274 post, and as I pointed out in the next >>54275 it's drawdown and negotiate.