Earlier quoted context omitted.
To be fair, the US has made a habit of losing against countries with GDPs closer to Ukraine than to Russia.
There’s gotta be some like inverse square law for how difficult a war is to win against a smaller and smaller nation.
The better metric is how interested you are in pursuing a war for the length of time necessary--it's a lot harder to get people to care about a war halfway across the other world than it is when it's prime farmland just next door.
(Note that the author here also has a series that touches on this topic--the Fremen Mirage.)