Quarantines for travellers entering the US will be required as part of the latest executive order signed by new president Joe Biden.
He did not specify how long people will be required to quarantine on arrival in the US.
The executive order says only that the quarantine period will be in accord with Centres for Disease Control and Prevention (CDC) guidelines.
The CDC recommends on its website that people stay home for seven days after arriving from abroad in most cases.
The measure will accompany pre-travel testing rules that were already due to be introduced on January 26.
Anyone arriving into the US from overseas will be required to produce proof of a negative Covid-19 test taken within 72 hours of departure – echoing newly introduced UK requirements.
People in the US must also wear masks during interstate travel, including on flights, buses, trains and boat or ferry services, as well as in airports.
The measures are part of a broad range of measures announced by the Biden administration to combat the spread of Covid-19.
Airlines and most airports already have their own mask rules in place, Travel Weekly in the US reported.
The mask mandate will provide “much needed back-up for flight attendants and aviation workers on the frontlines,” Sara Nelson, president of the Association of Flight Attendants-CWA union, said.