Try running tanks or planes without fuel, parts or ammo production. Covid was a little inconvenience compared to the supply chain nightmare a war could bring. It takes a TON of upkeep to keep a military rolling.
What does this even mean? That a private citizen is going to have better access to fuel, parts and ammo than the government?!?
No, but the US military has never had their homeland logistics fucked with in recent history. Sure you can’t easily destroy a Bradley APC, but it needs fuel that happens to be stored and transported in ways that are not as resistant to attack. And when the fuel runs out many vehicles are no longer useful in combat.
Or spare parts. Germany got their industries bombed like crazy in WW2. Even though their stuff was better on paper they didn’t have the parts to keep combat effective. Ask any veteran how reliable military vehicles are without constant maintenance.
This is hypothetical and all, but it’s not that big of a stretch of the imagination to see any American insurgency becoming a real pain in the ass for the military over months and years. And unlike Afghanistan they can’t simply withdraw when they’ve had enough.