Russia launched a military operation against Ukraine. NATO, led by the USA is assisting the Ukrainians to fight the Russians, without sending their own troops to Ukraine to fight ( being directly involved).
The USA officials have made it very clear that this is the best ROI the USA could have hopped for in weakening Russia, and all that without a single American soldier being shipped out in a body bag.
That, in a nutshell is a textbook example of a ‘proxy war’.