https://www.dhs.gov/news/2020/03/11/...l-proclamation
So it's only Schengen (which includes Iceland, Norway and Switzerland), and a lot more European countries are excepted in addition to the UK (Ireland, Cyprus, San Marino, Andorra, Vatican City, and others). Outright ban for foreigners who have been in the Schengen area the past 14 days.
US nationals will be funneled through a few select airports that will be determined soon, I imagine LHR and DUB.