President Donald Trump has said he will sign an executive order to temporarily suspend all immigration to the US because of the coronavirus.
On Twitter, he cited "the attack from the invisible enemy", as he calls the virus, and the need to protect the jobs of Americans, but did not give details.
It was not clear what programmes might be affected and whether the president would be able to carry out the order.
Critics say the government is using the pandemic to crack down on immigration.
Mr Trump's announcement late on Monday comes as the White House argues the worst of the pandemic is over and the country can begin reopening. The restrictions on people's movement, implemented by many states to curb the spread of the virus, have paralysed parts of the economy.
Over the last four weeks, more than 20 million Americans have made jobless claims. That amounts to roughly as many jobs as employers had added over the previous decade.
The US has over 787,000 confirmed cases of Covid-19 and more than 42,000 deaths, according to a tally by Johns Hopkins University, which is tracking the pandemic globally.
It was not immediately clear who could be affected by Mr Trump's decision, and the White House has not commented. Last month, the US suspended almost all visa processing, including for immigrants, because of the pandemic.
The US has already agreed with both Canada and Mexico to extend border restrictions on non-essential travel until at least mid-May.
Travel has also been sharply restricted from hard-hit European countries and China, though people with temporary work visas, students and business travellers are exempted.
In recent weeks, emergency powers have been used to expel thousands of undocumented migrants on the US border with Mexico. The public health measure lets officials override immigration laws, expediting removal processes.