I entertained the idea that his Holiness had been on a goodwill tour in the US when the European theatre went nuclear. The papal aircraft and a body double returned to Rome; however, the Pope's advisors had actually convinced him to stay put in the US, outside most likely target areas. He chose to set up a low-key anonymous residence at the National Shrine of Our Lady of Czestochowa in Doylestown, PA. It's located far enough from Philly and the Delaware River targets to have survived intact. Dressed as regular clergy, he helped the shrine staff organize and operate an enclave to shelter, feed, and medically treat the refugees.
Surprisingly, the enclave has had virtually no problems with raiders or marauders thus far. Then, the Swiss Guard are being assisted by assigned bodyguards from State Department's Bureau of Diplomatic Security and the odd Catholic member of the SEALs/Delta Force/etc. They patrol and overwatch a large radius from the refuge. Lots of things can blow up, breakdown, or perhaps die in their sleep far enough away and in such a convincing manner to redirect the potential attackers, helping to dissuade such riff-raff from coming too close.
(Wild rumors filter out about miraculous cures by a holy monk, and holy apparitions delivering holy vengeance against ill-intentioned interlopers.)
