I do not believe the United States could win a modern mechanized war today.
Hell, we can't even win asymmetrical warfare against enemies wearing sandals and wielding Kalashnikovs who heard goats for a living.
We are so far behind the curve.
We're really good at building cool, expensive congressional district gifts with lots of bells and whistles. It's all mired in the mud in Ukraine being used for Russian target practice.
It took decades to build the industrial base that was deployed in WW2.
It would take decades again to build an industrial base in the West with a similar capability.
And the biggest choke point might be the lack of skilled labor.
(Step 1. almost everyone has to go back to high school and do the 1940 curriculum)