Recommissioned US Navy ships

[Ursus Maior]

Building cosntruction isn't carrier technology though. First of all, you have a lot more construction workers than yard workers and second, while the Pentagon will need special infrastructure and security, specialists for that should be easier to come by than all the specialists involved in (re)building a super-carrier: Nuclear, radar and weapons technicians were not or hardly needed when (re)constructing the Pentagon.

And then there was only one Pentagon to reconstruct of course. In a war, you need to refit, repair, rebuild multiple carriers and construct new ones at the same time. That alone puts the US in a precarious position, since yard slots (i. e. large dry docks and even moorings) are hard to come by. That was already a problem during the Second World War.