The US government requires all air passengers from the United Kingdom to provide a negative corona test taken up to 72 hours before departure to the United States.
The new obligation, which takes effect on Monday, is set due to a new coronavirus variant that has emerged in Great Britain and is very contagious.
The US Center for Disease Prevention (CDC) said that all air passengers arriving from the UK must test negative to enter the US.
The decision is a reversal after the Trump administration told US airlines on Tuesday that it did not intend to make testing mandatory.
The new virus variant prompted many countries to close their borders with Great Britain.