We're not even talking about semiconductors. All of the basic goods you'd need to supply an army, or the industrial capacity for consumer goods that could be shifted to wartime production no longer exists. It's a problem the DoD has been talking about for years, but little action has happened.
Imports, Total Estimated Value by Country, 2017 (most recent) [0]: Canada: 26,200.3, Mexico: 23,541.0, [...] China: 6,159.7
Or energy?
"In 2020, the United States exported about 8.51 MMb/d and imported about 7.86 MMb/d of petroleum1, making the United States a net annual petroleum exporter for the first time since at least 1949." [1]
Or arms?
Based and manufacturing in the US: Honeywell, Huntington Ingalls (ex: Northrup Grumman Shipbuilding), L-3, UTC, General Dynamics, Northrop Grumman, Raytheon, Boeing, and Lockheed Martin [2]
If you're talking a full manpower, total war scenario that requires mobilization of the entire country's non-military industrial base...?
I think there's a reason there haven't been any wars like that between nuclear armed powers. Ever.
Because by the time it gets to that stage now, someone has fired nuclear weapons if they have them.