They would still need diesel to charge the batteries and get to our west coast wouldn’t they.
Not sure how electrics run and not looking it up, but, yes, i think so. But they don’t have to surface to run engines to recharge batteries.
If the US “saw” such a sub, they would not kill it; they would “escort” it, and then it would so whatever it was sent to do anyway, is what i think.
Some Navy guy out there? Input pleeze?