This is from the CDC listing the travel restrictions. Europe has been restricted from traveling to the US since March. Europe restricting the travel from the USA is fair considering the amount of new daily cases we are having. Some feel it's a tit for tat because the US hasn't relaxed it's own travel restrictions for Europe as well as the suspensions/restrictions of visa's being issued to foreigners to help protect American jobs. With unemployment being at an all time high I guess the logic is to fill the jobs with Americans before seeking workers from outside of the country. I also included a link regarding travel visa's.
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Suspension of Routine Visa Services
travel.state.gov