[apothegm]

Conventional being the key word. Yes, I know that usually is in contrast to nuclear warfare.

There’s really no motivation for China to attack the US (they have plenty of economic leverage and that would be far less costly to them than an invasion, and what would they even want with the territory of a conquered US?) but I suspect many of the reasons the US is assumed to be immune to invasion are far weaker in the face of an enemy with far more manpower and a near-bottomless supply of drones that also has the capacity to cut off our access to key parts, materials, and manufactured goods.