New York City has introduced quarantine rules for international travellers following emergence of new Covid variants in countries like the UK.
Mayor Bill de Blasio said all visitors would be ordered to stay for 14 days at the address they provided on arrival.
He said anyone arriving from the UK would be visited by sheriff’s deputies to ensure they abide by the rules.
Those who breach them will be fined $1,000 (£737) a day, Mr de Blasio warned.
About 18.4m coronavirus cases and more than 326,000 deaths have been recorded across the US, according to Johns Hopkins University.
New York City was at the epicentre of America’s coronavirus outbreak earlier this year, and has again become one of the country’s worst-affected states.