only if they can demonstrate a legitimate threat. they have not because they cannot. that is why they lost and will continue to do so. what happened elsewhere is moot given the extreme vetting processes that already exist in the US and that have so far protected the citizenry highly effectively. let's face it - the only reason for the ban is that Trump wanted to make a splash and not have other departments take credit for improved vetting down the road when his whole cabinet is in place.