Harry reveals so much ignorance in one statement.
There are no direct flights from these countries to America. They all have to travel through some other countries before coming here. Duncan traveled through Brussels, Belgium before he flew to Dulles and then on to Dallas-Ft. Worth.
You have to ban entrants from these countries, no matter whatever other nation they traveled through to get to America.
If the passport is stamped from a hot spot, REJECT!
Last time I checked, which wasn’t long ago, your passport/visa is stamped with whatever countries you have traveled to/from. It isn’t hard to discern which ones have been in Liberia, Siera Leone, etc.