My half-sister is married to an Iranian-born naturalized citizen. They have had plans since last year to go on a Viking river cruise in Europe in March. Several family members are urging them not to go (myself included). I think there is a very real possibility that my brother-in-law will not make it back into the country, but no way to know for sure until it happens. They are determined to go. Any advice I can give them on how to handle CBP challenges upon their return? Would you go if you were in their situation?