Measures come into effect on Monday
The US will require airline passengers from the UK to produce a negative Covid-19 test before their flight, in response to a new variant of coronavirus.
It is the latest country to announce new travel restrictions because of the variant spreading in the UK and elsewhere.
Airline passengers from the UK will need negative tests within three days of their trip and to provide the results to the airline, according to the Centres for Disease Control and Prevention.
The agency said the order will come into effect on Monday.
Airlines must deny boarding to any passenger who does not get a test.
The agency say that because of travel restrictions in place since March, air travel to the US from the UK is already down by 90%.